78321528457 has 2 divisors, whose sum is σ = 78321528458. Its totient is φ = 78321528456.

The previous prime is 78321528443. The next prime is 78321528499. The reversal of 78321528457 is 75482512387.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69592550416 + 8728978041 = 263804^2 + 93429^2 .

It is a cyclic number.

It is not a de Polignac number, because 78321528457 - 2¹⁵ = 78321495689 is a prime.

It is a super-2 number, since 2×78321528457² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78321528437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39160764228 + 39160764229.

It is an arithmetic number, because the mean of its divisors is an integer number (39160764229).

Almost surely, 2^78321528457 is an apocalyptic number.

It is an amenable number.

78321528457 is a deficient number, since it is larger than the sum of its proper divisors (1).

78321528457 is an equidigital number, since it uses as much as digits as its factorization.

78321528457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3763200, while the sum is 52.

The spelling of 78321528457 in words is "seventy-eight billion, three hundred twenty-one million, five hundred twenty-eight thousand, four hundred fifty-seven".