21913906 has 16 divisors (see below), whose sum is σ = 37840320. Its totient is φ = 9323280.

The previous prime is 21913861. The next prime is 21913933. The reversal of 21913906 is 60931912.

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 7 ways as a sum of consecutive naturals, for example, 3685 + ... + 7576.

It is an arithmetic number, because the mean of its divisors is an integer number (2365020).

Almost surely, 2^21913906 is an apocalyptic number.

21913906 is a deficient number, since it is larger than the sum of its proper divisors (15926414).

21913906 is a wasteful number, since it uses less digits than its factorization.

21913906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11409.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21913906 is about 4681.2291121029. The cubic root of 21913906 is about 279.8379419366.

The spelling of 21913906 in words is "twenty-one million, nine hundred thirteen thousand, nine hundred six".