21699456 has 32 divisors (see below), whose sum is σ = 57640200. Its totient is φ = 7233024.

The previous prime is 21699449. The next prime is 21699481. The reversal of 21699456 is 65499612.

It is a happy number.

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

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

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, 27871 + ... + 28638.

Almost surely, 2^21699456 is an apocalyptic number.

It is an amenable number.

21699456 is an abundant number, since it is smaller than the sum of its proper divisors (35940744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21699456 is an equidigital number, since it uses as much as digits as its factorization.

21699456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56526 (or 56514 counting only the distinct ones).

The product of its digits is 116640, while the sum is 42.

The square root of 21699456 is about 4658.2674890994. The cubic root of 21699456 is about 278.9221144088.

It can be divided in two parts, 21699 and 456, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21699456 in words is "twenty-one million, six hundred ninety-nine thousand, four hundred fifty-six".