87638021 has 2 divisors, whose sum is σ = 87638022. Its totient is φ = 87638020.

The previous prime is 87637967. The next prime is 87638101. The reversal of 87638021 is 12083678.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 86397025 + 1240996 = 9295^2 + 1114^2 .

It is a cyclic number.

It is not a de Polignac number, because 87638021 - 2¹⁴ = 87621637 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87638321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43819010 + 43819011.

It is an arithmetic number, because the mean of its divisors is an integer number (43819011).

Almost surely, 2^87638021 is an apocalyptic number.

It is an amenable number.

87638021 is a deficient number, since it is larger than the sum of its proper divisors (1).

87638021 is an equidigital number, since it uses as much as digits as its factorization.

87638021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 87638021 is about 9361.5180927027. The cubic root of 87638021 is about 444.1853056691.

The spelling of 87638021 in words is "eighty-seven million, six hundred thirty-eight thousand, twenty-one".