87121513 has 2 divisors, whose sum is σ = 87121514. Its totient is φ = 87121512.

The previous prime is 87121487. The next prime is 87121523. The reversal of 87121513 is 31512178.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 86620249 + 501264 = 9307^2 + 708^2 .

It is a cyclic number.

It is not a de Polignac number, because 87121513 - 2²⁵ = 53567081 is a prime.

It is not a weakly prime, because it can be changed into another prime (87121523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43560756 + 43560757.

It is an arithmetic number, because the mean of its divisors is an integer number (43560757).

Almost surely, 2^87121513 is an apocalyptic number.

It is an amenable number.

87121513 is a deficient number, since it is larger than the sum of its proper divisors (1).

87121513 is an equidigital number, since it uses as much as digits as its factorization.

87121513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 28.

The square root of 87121513 is about 9333.8905607469. The cubic root of 87121513 is about 443.3109611766.

The spelling of 87121513 in words is "eighty-seven million, one hundred twenty-one thousand, five hundred thirteen".