161399045025 has 27 divisors (see below), whose sum is σ = 289094416819. Its totient is φ = 86076276720.

The previous prime is 161399045023. The next prime is 161399045063. The reversal of 161399045025 is 520540993161.

The square root of 161399045025 is 401745.

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

161399045025 is a `hidden beast` number, since 1 + 6 + 139 + 9 + 0 + 4 + 502 + 5 = 666.

It can be written as a sum of positive squares in only one way, i.e., 58103656209 + 103295388816 = 241047^2 + 321396^2 .

It is not a de Polignac number, because 161399045025 - 2¹ = 161399045023 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161399045023) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 6012784 + ... + 6039566.

Almost surely, 2^161399045025 is an apocalyptic number.

161399045025 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

161399045025 is the 401745-th square number.

161399045025 is the 200873-rd centered octagonal number.

It is an amenable number.

161399045025 is a deficient number, since it is larger than the sum of its proper divisors (127695371794).

161399045025 is an frugal number, since it uses more digits than its factorization.

161399045025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53582 (or 26791 counting only the distinct ones).

The product of its (nonzero) digits is 291600, while the sum is 45.

The spelling of 161399045025 in words is "one hundred sixty-one billion, three hundred ninety-nine million, forty-five thousand, twenty-five".