21372985 has 4 divisors (see below), whose sum is σ = 25647588. Its totient is φ = 17098384.

The previous prime is 21372977. The next prime is 21372991. The reversal of 21372985 is 58927312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16426809 + 4946176 = 4053^2 + 2224^2 .

It is a cyclic number.

It is not a de Polignac number, because 21372985 - 2³ = 21372977 is a prime.

It is a Duffinian 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, 2137294 + ... + 2137303.

It is an arithmetic number, because the mean of its divisors is an integer number (6411897).

Almost surely, 2^21372985 is an apocalyptic number.

It is an amenable number.

21372985 is a deficient number, since it is larger than the sum of its proper divisors (4274603).

21372985 is an equidigital number, since it uses as much as digits as its factorization.

21372985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4274602.

The product of its digits is 30240, while the sum is 37.

The square root of 21372985 is about 4623.0925796484. The cubic root of 21372985 is about 277.5162342043.

The spelling of 21372985 in words is "twenty-one million, three hundred seventy-two thousand, nine hundred eighty-five".