87931421 has 2 divisors, whose sum is σ = 87931422. Its totient is φ = 87931420.

The previous prime is 87931397. The next prime is 87931427. The reversal of 87931421 is 12413978.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70375321 + 17556100 = 8389^2 + 4190^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-87931421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87931427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43965710 + 43965711.

It is an arithmetic number, because the mean of its divisors is an integer number (43965711).

Almost surely, 2^87931421 is an apocalyptic number.

It is an amenable number.

87931421 is a deficient number, since it is larger than the sum of its proper divisors (1).

87931421 is an equidigital number, since it uses as much as digits as its factorization.

87931421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 87931421 is about 9377.1755342427. The cubic root of 87931421 is about 444.6804438962.

The spelling of 87931421 in words is "eighty-seven million, nine hundred thirty-one thousand, four hundred twenty-one".