21551459 has 2 divisors, whose sum is σ = 21551460. Its totient is φ = 21551458.

The previous prime is 21551449. The next prime is 21551503. The reversal of 21551459 is 95415512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21551459 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21551429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775729 + 10775730.

It is an arithmetic number, because the mean of its divisors is an integer number (10775730).

Almost surely, 2^21551459 is an apocalyptic number.

21551459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21551459 is an equidigital number, since it uses as much as digits as its factorization.

21551459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9000, while the sum is 32.

The square root of 21551459 is about 4642.3548981094. The cubic root of 21551459 is about 278.2865556186.

The spelling of 21551459 in words is "twenty-one million, five hundred fifty-one thousand, four hundred fifty-nine".