21523408 has 20 divisors (see below), whose sum is σ = 41925888. Its totient is φ = 10703840.

The previous prime is 21523399. The next prime is 21523417. The reversal of 21523408 is 80432512.

It is an interprime number because it is at equal distance from previous prime (21523399) and next prime (21523417).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 466 + ... + 6577.

Almost surely, 2^21523408 is an apocalyptic number.

It is an amenable number.

21523408 is a deficient number, since it is larger than the sum of its proper divisors (20402480).

21523408 is a wasteful number, since it uses less digits than its factorization.

21523408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7242 (or 7236 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 21523408 is about 4639.3327106385. The cubic root of 21523408 is about 278.1657655686.

The spelling of 21523408 in words is "twenty-one million, five hundred twenty-three thousand, four hundred eight".