78999581 has 2 divisors, whose sum is σ = 78999582. Its totient is φ = 78999580.

The previous prime is 78999553. The next prime is 78999593. The reversal of 78999581 is 18599987.

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., 45010681 + 33988900 = 6709^2 + 5830^2 .

It is a cyclic number.

It is not a de Polignac number, because 78999581 - 2¹⁸ = 78737437 is a prime.

It is a super-2 number, since 2×78999581² = 12481867596351122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78999541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39499790 + 39499791.

It is an arithmetic number, because the mean of its divisors is an integer number (39499791).

Almost surely, 2^78999581 is an apocalyptic number.

It is an amenable number.

78999581 is a deficient number, since it is larger than the sum of its proper divisors (1).

78999581 is an equidigital number, since it uses as much as digits as its factorization.

78999581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1632960, while the sum is 56.

The square root of 78999581 is about 8888.1708466928. The cubic root of 78999581 is about 429.0832841097.

The spelling of 78999581 in words is "seventy-eight million, nine hundred ninety-nine thousand, five hundred eighty-one".