21906986 has 8 divisors (see below), whose sum is σ = 32919744. Its totient is φ = 10933740.

The previous prime is 21906961. The next prime is 21907007. The reversal of 21906986 is 68960912.

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 8450 + ... + 10733.

It is an arithmetic number, because the mean of its divisors is an integer number (4114968).

Almost surely, 2^21906986 is an apocalyptic number.

21906986 is a deficient number, since it is larger than the sum of its proper divisors (11012758).

21906986 is a wasteful number, since it uses less digits than its factorization.

21906986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19756.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 21906986 is about 4680.4899316204. The cubic root of 21906986 is about 279.8084829798.

The spelling of 21906986 in words is "twenty-one million, nine hundred six thousand, nine hundred eighty-six".