87513821 has 2 divisors, whose sum is σ = 87513822. Its totient is φ = 87513820.

The previous prime is 87513817. The next prime is 87513823. The reversal of 87513821 is 12831578.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57592921 + 29920900 = 7589^2 + 5470^2 .

It is a cyclic number.

It is not a de Polignac number, because 87513821 - 2² = 87513817 is a prime.

Together with 87513823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87513823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43756910 + 43756911.

It is an arithmetic number, because the mean of its divisors is an integer number (43756911).

Almost surely, 2^87513821 is an apocalyptic number.

It is an amenable number.

87513821 is a deficient number, since it is larger than the sum of its proper divisors (1).

87513821 is an equidigital number, since it uses as much as digits as its factorization.

87513821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 35.

The square root of 87513821 is about 9354.8822012893. The cubic root of 87513821 is about 443.9753743478.

The spelling of 87513821 in words is "eighty-seven million, five hundred thirteen thousand, eight hundred twenty-one".