21120637 has 2 divisors, whose sum is σ = 21120638. Its totient is φ = 21120636.

The previous prime is 21120629. The next prime is 21120661. The reversal of 21120637 is 73602112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18096516 + 3024121 = 4254^2 + 1739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120637 - 2³ = 21120629 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 (21120607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560318 + 10560319.

It is an arithmetic number, because the mean of its divisors is an integer number (10560319).

Almost surely, 2^21120637 is an apocalyptic number.

It is an amenable number.

21120637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120637 is an equidigital number, since it uses as much as digits as its factorization.

21120637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21120637 is about 4595.7194213746. The cubic root of 21120637 is about 276.4197081748.

Adding to 21120637 its reverse (73602112), we get a palindrome (94722749).

The spelling of 21120637 in words is "twenty-one million, one hundred twenty thousand, six hundred thirty-seven".