21126331801 has 3 divisors (see below), whose sum is σ = 21126477151. Its totient is φ = 21126186452.

The previous prime is 21126331789. The next prime is 21126331813. The reversal of 21126331801 is 10813362112.

It is a happy number.

The square root of 21126331801 is 145349.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (21126331789) and next prime (21126331813).

It can be written as a sum of positive squares in only one way, i.e., 6256968201 + 14869363600 = 79101^2 + 121940^2 .

It is not a de Polignac number, because 21126331801 - 2⁵ = 21126331769 is a prime.

It is a super-3 number, since 3×21126331801³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21126331801.

It is not an unprimeable number, because it can be changed into a prime (21126331871) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 72675 + ... + 218023.

Almost surely, 2^21126331801 is an apocalyptic number.

21126331801 is the 145349-th square number.

21126331801 is the 72675-th centered octagonal number.

It is an amenable number.

21126331801 is a deficient number, since it is larger than the sum of its proper divisors (145350).

21126331801 is an frugal number, since it uses more digits than its factorization.

21126331801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290698 (or 145349 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

Adding to 21126331801 its reverse (10813362112), we get a palindrome (31939693913).

The spelling of 21126331801 in words is "twenty-one billion, one hundred twenty-six million, three hundred thirty-one thousand, eight hundred one".