21642103531 has 2 divisors, whose sum is σ = 21642103532. Its totient is φ = 21642103530.

The previous prime is 21642103523. The next prime is 21642103579. The reversal of 21642103531 is 13530124612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21642103531 - 2³ = 21642103523 is a prime.

It is a super-2 number, since 2×21642103531² (a number of 21 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 21642103531.

It is not a weakly prime, because it can be changed into another prime (21642103591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821051765 + 10821051766.

It is an arithmetic number, because the mean of its divisors is an integer number (10821051766).

Almost surely, 2^21642103531 is an apocalyptic number.

21642103531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642103531 is an equidigital number, since it uses as much as digits as its factorization.

21642103531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 28.

The spelling of 21642103531 in words is "twenty-one billion, six hundred forty-two million, one hundred three thousand, five hundred thirty-one".