21458531 has 2 divisors, whose sum is σ = 21458532. Its totient is φ = 21458530.

The previous prime is 21458527. The next prime is 21458597. The reversal of 21458531 is 13585412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21458531 - 2² = 21458527 is a prime.

It is a super-2 number, since 2×21458531² = 920937105355922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21458494 and 21458503.

It is not a weakly prime, because it can be changed into another prime (21451531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10729265 + 10729266.

It is an arithmetic number, because the mean of its divisors is an integer number (10729266).

Almost surely, 2^21458531 is an apocalyptic number.

21458531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21458531 is an equidigital number, since it uses as much as digits as its factorization.

21458531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4800, while the sum is 29.

The square root of 21458531 is about 4632.3353721422. The cubic root of 21458531 is about 277.8859969387.

The spelling of 21458531 in words is "twenty-one million, four hundred fifty-eight thousand, five hundred thirty-one".