87221581 has 2 divisors, whose sum is σ = 87221582. Its totient is φ = 87221580.

The previous prime is 87221579. The next prime is 87221591. The reversal of 87221581 is 18512278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75429225 + 11792356 = 8685^2 + 3434^2 .

It is a cyclic number.

It is not a de Polignac number, because 87221581 - 2¹ = 87221579 is a prime.

It is a super-2 number, since 2×87221581² = 15215208384279122, which contains 22 as substring.

Together with 87221579, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87221551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43610790 + 43610791.

It is an arithmetic number, because the mean of its divisors is an integer number (43610791).

Almost surely, 2^87221581 is an apocalyptic number.

It is an amenable number.

87221581 is a deficient number, since it is larger than the sum of its proper divisors (1).

87221581 is an equidigital number, since it uses as much as digits as its factorization.

87221581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8960, while the sum is 34.

The square root of 87221581 is about 9339.2494880477. The cubic root of 87221581 is about 443.4806256145.

The spelling of 87221581 in words is "eighty-seven million, two hundred twenty-one thousand, five hundred eighty-one".