87817924021 has 2 divisors, whose sum is σ = 87817924022. Its totient is φ = 87817924020.

The previous prime is 87817924013. The next prime is 87817924079. The reversal of 87817924021 is 12042971878.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 87394140625 + 423783396 = 295625^2 + 20586^2 .

It is a cyclic number.

It is not a de Polignac number, because 87817924021 - 2³ = 87817924013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87817924121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43908962010 + 43908962011.

It is an arithmetic number, because the mean of its divisors is an integer number (43908962011).

Almost surely, 2^87817924021 is an apocalyptic number.

It is an amenable number.

87817924021 is a deficient number, since it is larger than the sum of its proper divisors (1).

87817924021 is an equidigital number, since it uses as much as digits as its factorization.

87817924021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 451584, while the sum is 49.

The spelling of 87817924021 in words is "eighty-seven billion, eight hundred seventeen million, nine hundred twenty-four thousand, twenty-one".