21642916 has 12 divisors (see below), whose sum is σ = 38799180. Its totient is φ = 10557440.

The previous prime is 21642899. The next prime is 21642923. The reversal of 21642916 is 61924612.

It can be written as a sum of positive squares in 2 ways, for example, as 1572516 + 20070400 = 1254^2 + 4480^2 .

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, 65821 + ... + 66148.

It is an arithmetic number, because the mean of its divisors is an integer number (3233265).

Almost surely, 2^21642916 is an apocalyptic number.

It is an amenable number.

21642916 is a deficient number, since it is larger than the sum of its proper divisors (17156264).

21642916 is a wasteful number, since it uses less digits than its factorization.

21642916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132014 (or 132012 counting only the distinct ones).

The product of its digits is 5184, while the sum is 31.

The square root of 21642916 is about 4652.1947508676. The cubic root of 21642916 is about 278.6796509852.

The spelling of 21642916 in words is "twenty-one million, six hundred forty-two thousand, nine hundred sixteen".