87187921 has 2 divisors, whose sum is σ = 87187922. Its totient is φ = 87187920.

The previous prime is 87187879. The next prime is 87187937. The reversal of 87187921 is 12978178.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49843600 + 37344321 = 7060^2 + 6111^2 .

It is a cyclic number.

It is not a de Polignac number, because 87187921 - 2¹¹ = 87185873 is a prime.

It is not a weakly prime, because it can be changed into another prime (87187981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43593960 + 43593961.

It is an arithmetic number, because the mean of its divisors is an integer number (43593961).

Almost surely, 2^87187921 is an apocalyptic number.

It is an amenable number.

87187921 is a deficient number, since it is larger than the sum of its proper divisors (1).

87187921 is an equidigital number, since it uses as much as digits as its factorization.

87187921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 43.

The square root of 87187921 is about 9337.4472421535. The cubic root of 87187921 is about 443.4235698631.

The spelling of 87187921 in words is "eighty-seven million, one hundred eighty-seven thousand, nine hundred twenty-one".