21242659 has 2 divisors, whose sum is σ = 21242660. Its totient is φ = 21242658.

The previous prime is 21242651. The next prime is 21242681. The reversal of 21242659 is 95624212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21242659 - 2³ = 21242651 is a prime.

It is a super-2 number, since 2×21242659² = 902501122780562, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21242659.

It is not a weakly prime, because it can be changed into another prime (21242651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621329 + 10621330.

It is an arithmetic number, because the mean of its divisors is an integer number (10621330).

Almost surely, 2^21242659 is an apocalyptic number.

21242659 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242659 is an equidigital number, since it uses as much as digits as its factorization.

21242659 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 31.

The square root of 21242659 is about 4608.9759166218. The cubic root of 21242659 is about 276.9510137671.

The spelling of 21242659 in words is "twenty-one million, two hundred forty-two thousand, six hundred fifty-nine".