21913523 has 2 divisors, whose sum is σ = 21913524. Its totient is φ = 21913522.

The previous prime is 21913519. The next prime is 21913543. The reversal of 21913523 is 32531912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21913523 - 2² = 21913519 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21913492 and 21913501.

It is not a weakly prime, because it can be changed into another prime (21913513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10956761 + 10956762.

It is an arithmetic number, because the mean of its divisors is an integer number (10956762).

Almost surely, 2^21913523 is an apocalyptic number.

21913523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21913523 is an equidigital number, since it uses as much as digits as its factorization.

21913523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 26.

The square root of 21913523 is about 4681.1882038645. The cubic root of 21913523 is about 279.8363116391.

The spelling of 21913523 in words is "twenty-one million, nine hundred thirteen thousand, five hundred twenty-three".