21550637 has 2 divisors, whose sum is σ = 21550638. Its totient is φ = 21550636.

The previous prime is 21550601. The next prime is 21550643. The reversal of 21550637 is 73605512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17732521 + 3818116 = 4211^2 + 1954^2 .

It is a cyclic number.

It is not a de Polignac number, because 21550637 - 2¹⁰ = 21549613 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21550657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775318 + 10775319.

It is an arithmetic number, because the mean of its divisors is an integer number (10775319).

Almost surely, 2^21550637 is an apocalyptic number.

It is an amenable number.

21550637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21550637 is an equidigital number, since it uses as much as digits as its factorization.

21550637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6300, while the sum is 29.

The square root of 21550637 is about 4642.2663646111. The cubic root of 21550637 is about 278.2830175062.

The spelling of 21550637 in words is "twenty-one million, five hundred fifty thousand, six hundred thirty-seven".