21309926 has 16 divisors (see below), whose sum is σ = 35015760. Its totient is φ = 9646080.

The previous prime is 21309913. The next prime is 21309973. The reversal of 21309926 is 62990312.

It is a super-2 number, since 2×21309926² = 908225892250952, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21309892 and 21309901.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3770 + ... + 7538.

It is an arithmetic number, because the mean of its divisors is an integer number (2188485).

Almost surely, 2^21309926 is an apocalyptic number.

21309926 is a deficient number, since it is larger than the sum of its proper divisors (13705834).

21309926 is a wasteful number, since it uses less digits than its factorization.

21309926 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4039.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 21309926 is about 4616.2675399071. The cubic root of 21309926 is about 277.2430367531.

The spelling of 21309926 in words is "twenty-one million, three hundred nine thousand, nine hundred twenty-six".