78173681 has 2 divisors, whose sum is σ = 78173682. Its totient is φ = 78173680.

The previous prime is 78173671. The next prime is 78173687. The reversal of 78173681 is 18637187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 40768225 + 37405456 = 6385^2 + 6116^2 .

It is a cyclic number.

It is not a de Polignac number, because 78173681 - 2⁶ = 78173617 is a prime.

It is a super-2 number, since 2×78173681² = 12222248802179522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78173687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39086840 + 39086841.

It is an arithmetic number, because the mean of its divisors is an integer number (39086841).

Almost surely, 2^78173681 is an apocalyptic number.

It is an amenable number.

78173681 is a deficient number, since it is larger than the sum of its proper divisors (1).

78173681 is an equidigital number, since it uses as much as digits as its factorization.

78173681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 41.

The square root of 78173681 is about 8841.5881491958. The cubic root of 78173681 is about 427.5827611278.

The spelling of 78173681 in words is "seventy-eight million, one hundred seventy-three thousand, six hundred eighty-one".