21015344401 has 4 divisors (see below), whose sum is σ = 21027334372. Its totient is φ = 21003354432.

The previous prime is 21015344381. The next prime is 21015344437. The reversal of 21015344401 is 10444351012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1064064400 + 19951280001 = 32620^2 + 141249^2 .

It is a cyclic number.

It is not a de Polignac number, because 21015344401 - 2⁵ = 21015344369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21015345401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5992356 + ... + 5995861.

It is an arithmetic number, because the mean of its divisors is an integer number (5256833593).

Almost surely, 2^21015344401 is an apocalyptic number.

It is an amenable number.

21015344401 is a deficient number, since it is larger than the sum of its proper divisors (11989971).

21015344401 is a wasteful number, since it uses less digits than its factorization.

21015344401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11989970.

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 21015344401 its reverse (10444351012), we get a palindrome (31459695413).

The spelling of 21015344401 in words is "twenty-one billion, fifteen million, three hundred forty-four thousand, four hundred one".