21531206659 has 2 divisors, whose sum is σ = 21531206660. Its totient is φ = 21531206658.

The previous prime is 21531206579. The next prime is 21531206663. The reversal of 21531206659 is 95660213512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21531206659 - 2¹⁵ = 21531173891 is a prime.

It is not a weakly prime, because it can be changed into another prime (21531236659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765603329 + 10765603330.

It is an arithmetic number, because the mean of its divisors is an integer number (10765603330).

Almost surely, 2^21531206659 is an apocalyptic number.

21531206659 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531206659 is an equidigital number, since it uses as much as digits as its factorization.

21531206659 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 97200, while the sum is 40.

The spelling of 21531206659 in words is "twenty-one billion, five hundred thirty-one million, two hundred six thousand, six hundred fifty-nine".