21660401056431 has 32 divisors (see below), whose sum is σ = 29865169152000. Its totient is φ = 13954655301120.

The previous prime is 21660401056409. The next prime is 21660401056477. The reversal of 21660401056431 is 13465010406612.

It is not a de Polignac number, because 21660401056431 - 2¹⁰ = 21660401055407 is a prime.

It is a super-2 number, since 2×21660401056431² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21660401056431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660401057431) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 109519170 + ... + 109716768.

It is an arithmetic number, because the mean of its divisors is an integer number (933286536000).

Almost surely, 2^{21660401056431} is an apocalyptic number.

21660401056431 is a deficient number, since it is larger than the sum of its proper divisors (8204768095569).

21660401056431 is a wasteful number, since it uses less digits than its factorization.

21660401056431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206079.

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 21660401056431 in words is "twenty-one trillion, six hundred sixty billion, four hundred one million, fifty-six thousand, four hundred thirty-one".