21074038561 has 9 divisors (see below), whose sum is σ = 21218591793. Its totient is φ = 20930466420.

The previous prime is 21074038549. The next prime is 21074038631. The reversal of 21074038561 is 16583047012.

The square root of 21074038561 is 145169.

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

It is not a de Polignac number, because 21074038561 - 2⁵ = 21074038529 is a prime.

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 21074038561.

It is not an unprimeable number, because it can be changed into a prime (21074038541) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 25984846 + ... + 25985656.

Almost surely, 2^21074038561 is an apocalyptic number.

21074038561 is the 145169-th square number.

21074038561 is the 72585-th centered octagonal number.

It is an amenable number.

21074038561 is a deficient number, since it is larger than the sum of its proper divisors (144553232).

21074038561 is an frugal number, since it uses more digits than its factorization.

21074038561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1980 (or 990 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 37.

The spelling of 21074038561 in words is "twenty-one billion, seventy-four million, thirty-eight thousand, five hundred sixty-one".