21637045 has 24 divisors (see below), whose sum is σ = 27858600. Its totient is φ = 16111872.

The previous prime is 21637019. The next prime is 21637069. The reversal of 21637045 is 54073612.

It can be written as a sum of positive squares in 12 ways, for example, as 237169 + 21399876 = 487^2 + 4626^2 .

It is not a de Polignac number, because 21637045 - 2⁵ = 21637013 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 198451 + ... + 198559.

It is an arithmetic number, because the mean of its divisors is an integer number (1160775).

Almost surely, 2^21637045 is an apocalyptic number.

It is an amenable number.

21637045 is a deficient number, since it is larger than the sum of its proper divisors (6221555).

21637045 is a wasteful number, since it uses less digits than its factorization.

21637045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217 (or 180 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21637045 is about 4651.5637155692. The cubic root of 21637045 is about 278.6544498802.

The spelling of 21637045 in words is "twenty-one million, six hundred thirty-seven thousand, forty-five".