81078408966025 has 27 divisors (see below), whose sum is σ = 104125249674901. Its totient is φ = 62625072920480.

The previous prime is 81078408966001. The next prime is 81078408966073. The reversal of 81078408966025 is 52066980487018.

It is a happy number.

The square root of 81078408966025 is 9004355.

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 1114466596489 + 79963942369536 = 1055683^2 + 8942256^2 .

It is not a de Polignac number, because 81078408966025 - 2¹⁵ = 81078408933257 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1305600426 + ... + 1305662524.

Almost surely, 2^{81078408966025} is an apocalyptic number.

81078408966025 is the 9004355-th square number.

81078408966025 is the 4502178-th centered octagonal number.

It is an amenable number.

81078408966025 is a deficient number, since it is larger than the sum of its proper divisors (23046840708876).

81078408966025 is an frugal number, since it uses more digits than its factorization.

81078408966025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124266 (or 62133 counting only the distinct ones).

The product of its (nonzero) digits is 46448640, while the sum is 64.

The spelling of 81078408966025 in words is "eighty-one trillion, seventy-eight billion, four hundred eight million, nine hundred sixty-six thousand, twenty-five".