21005696 has 32 divisors (see below), whose sum is σ = 42054600. Its totient is φ = 10450944.

The previous prime is 21005689. The next prime is 21005701. The reversal of 21005696 is 69650012.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48296 + ... + 48728.

Almost surely, 2^21005696 is an apocalyptic number.

It is an amenable number.

21005696 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21005696 is an equidigital number, since it uses as much as digits as its factorization.

21005696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 826 (or 814 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 21005696 is about 4583.1971373704. The cubic root of 21005696 is about 275.9173595611.

Subtracting 21005696 from its reverse (69650012), we obtain a triangular number (48644316 = T₉₈₆₃).

The spelling of 21005696 in words is "twenty-one million, five thousand, six hundred ninety-six".