20871637 has 2 divisors, whose sum is σ = 20871638. Its totient is φ = 20871636.

The previous prime is 20871629. The next prime is 20871659. The reversal of 20871637 is 73617802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19131876 + 1739761 = 4374^2 + 1319^2 .

It is a cyclic number.

It is not a de Polignac number, because 20871637 - 2³ = 20871629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20871667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10435818 + 10435819.

It is an arithmetic number, because the mean of its divisors is an integer number (10435819).

Almost surely, 2^20871637 is an apocalyptic number.

It is an amenable number.

20871637 is a deficient number, since it is larger than the sum of its proper divisors (1).

20871637 is an equidigital number, since it uses as much as digits as its factorization.

20871637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 20871637 is about 4568.5486754548. The cubic root of 20871637 is about 275.3291353918.

The spelling of 20871637 in words is "twenty million, eight hundred seventy-one thousand, six hundred thirty-seven".