87778931 has 2 divisors, whose sum is σ = 87778932. Its totient is φ = 87778930.

The previous prime is 87778919. The next prime is 87778937. The reversal of 87778931 is 13987778.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 87778931 - 2¹⁸ = 87516787 is a prime.

It is a super-2 number, since 2×87778931² = 15410281455005522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 87778931.

It is not a weakly prime, because it can be changed into another prime (87778937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43889465 + 43889466.

It is an arithmetic number, because the mean of its divisors is an integer number (43889466).

Almost surely, 2^87778931 is an apocalyptic number.

87778931 is a deficient number, since it is larger than the sum of its proper divisors (1).

87778931 is an equidigital number, since it uses as much as digits as its factorization.

87778931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 592704, while the sum is 50.

The square root of 87778931 is about 9369.0410928760. The cubic root of 87778931 is about 444.4232413473.

The spelling of 87778931 in words is "eighty-seven million, seven hundred seventy-eight thousand, nine hundred thirty-one".