78102921961 has 9 divisors (see below), whose sum is σ = 79619465989. Its totient is φ = 76614749536.

The previous prime is 78102921947. The next prime is 78102921973. The reversal of 78102921961 is 16912920187.

The square root of 78102921961 is 279469.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 3803065561 + 74299856400 = 61669^2 + 272580^2 .

It is not a de Polignac number, because 78102921961 - 2¹¹ = 78102919913 is a prime.

It is a super-2 number, since 2×78102921961² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78102921901) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 14809221 + ... + 14814493.

Almost surely, 2^78102921961 is an apocalyptic number.

78102921961 is the 279469-th square number.

78102921961 is the 139735-th centered octagonal number.

It is an amenable number.

78102921961 is a deficient number, since it is larger than the sum of its proper divisors (1516544028).

78102921961 is an frugal number, since it uses more digits than its factorization.

78102921961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10652 (or 5326 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 46.

The spelling of 78102921961 in words is "seventy-eight billion, one hundred two million, nine hundred twenty-one thousand, nine hundred sixty-one".