87513381521 has 2 divisors, whose sum is σ = 87513381522. Its totient is φ = 87513381520.

The previous prime is 87513381503. The next prime is 87513381523. The reversal of 87513381521 is 12518331578.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60582930496 + 26930451025 = 246136^2 + 164105^2 .

It is a cyclic number.

It is not a de Polignac number, because 87513381521 - 2⁶ = 87513381457 is a prime.

Together with 87513381523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (87513381523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43756690760 + 43756690761.

It is an arithmetic number, because the mean of its divisors is an integer number (43756690761).

Almost surely, 2^87513381521 is an apocalyptic number.

It is an amenable number.

87513381521 is a deficient number, since it is larger than the sum of its proper divisors (1).

87513381521 is an equidigital number, since it uses as much as digits as its factorization.

87513381521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 201600, while the sum is 44.

The spelling of 87513381521 in words is "eighty-seven billion, five hundred thirteen million, three hundred eighty-one thousand, five hundred twenty-one".