87390217 has 12 divisors (see below), whose sum is σ = 93611700. Its totient is φ = 81299456.

The previous prime is 87390211. The next prime is 87390223. The reversal of 87390217 is 71209378.

It is an interprime number because it is at equal distance from previous prime (87390211) and next prime (87390223).

It can be written as a sum of positive squares in 2 ways, for example, as 61011721 + 26378496 = 7811^2 + 5136^2 .

It is a de Polignac number, because none of the positive numbers 2^k-87390217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87390211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 194409 + ... + 194857.

It is an arithmetic number, because the mean of its divisors is an integer number (7800975).

Almost surely, 2^87390217 is an apocalyptic number.

87390217 is the 7633-rd pentagonal number.

It is an amenable number.

87390217 is a deficient number, since it is larger than the sum of its proper divisors (6221483).

87390217 is a wasteful number, since it uses less digits than its factorization.

87390217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680 (or 573 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 87390217 is about 9348.2734769582. The cubic root of 87390217 is about 443.7662531374.

The spelling of 87390217 in words is "eighty-seven million, three hundred ninety thousand, two hundred seventeen".