21021003826 has 4 divisors (see below), whose sum is σ = 31531505742. Its totient is φ = 10510501912.

The previous prime is 21021003823. The next prime is 21021003827. The reversal of 21021003826 is 62830012012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 21010212601 + 10791225 = 144949^2 + 3285^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21021003826.

It is not an unprimeable number, because it can be changed into a prime (21021003823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5255250955 + ... + 5255250958.

Almost surely, 2^21021003826 is an apocalyptic number.

21021003826 is a deficient number, since it is larger than the sum of its proper divisors (10510501916).

21021003826 is a wasteful number, since it uses less digits than its factorization.

21021003826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10510501915.

The product of its (nonzero) digits is 1152, while the sum is 25.

Adding to 21021003826 its reverse (62830012012), we get a palindrome (83851015838).

The spelling of 21021003826 in words is "twenty-one billion, twenty-one million, three thousand, eight hundred twenty-six".