21573986 has 16 divisors (see below), whose sum is σ = 39159936. Its totient is φ = 8702016.

The previous prime is 21573983. The next prime is 21573991. The reversal of 21573986 is 68937512.

It is not an unprimeable number, because it can be changed into a prime (21573983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45086 + ... + 45561.

It is an arithmetic number, because the mean of its divisors is an integer number (2447496).

Almost surely, 2^21573986 is an apocalyptic number.

21573986 is a deficient number, since it is larger than the sum of its proper divisors (17585950).

21573986 is a wasteful number, since it uses less digits than its factorization.

21573986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90673.

The product of its digits is 90720, while the sum is 41.

The square root of 21573986 is about 4644.7805114989. The cubic root of 21573986 is about 278.3834829815.

The spelling of 21573986 in words is "twenty-one million, five hundred seventy-three thousand, nine hundred eighty-six".