21601386531 has 8 divisors (see below), whose sum is σ = 32002054160. Its totient is φ = 14400924336.

The previous prime is 21601386517. The next prime is 21601386533. The reversal of 21601386531 is 13568310612.

It is not a de Polignac number, because 21601386531 - 2⁶ = 21601386467 is a prime.

It is a super-2 number, since 2×21601386531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21601386533) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 400025650 + ... + 400025703.

It is an arithmetic number, because the mean of its divisors is an integer number (4000256770).

Almost surely, 2^21601386531 is an apocalyptic number.

21601386531 is a deficient number, since it is larger than the sum of its proper divisors (10400667629).

21601386531 is an equidigital number, since it uses as much as digits as its factorization.

21601386531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 800051362 (or 800051356 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The spelling of 21601386531 in words is "twenty-one billion, six hundred one million, three hundred eighty-six thousand, five hundred thirty-one".