161639977 has 2 divisors, whose sum is σ = 161639978. Its totient is φ = 161639976.

The previous prime is 161639957. The next prime is 161639981. The reversal of 161639977 is 779936161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 131125401 + 30514576 = 11451^2 + 5524^2 .

It is a cyclic number.

It is not a de Polignac number, because 161639977 - 2¹¹ = 161637929 is a prime.

It is a super-2 number, since 2×161639977² = 52254964329121058, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161639977.

It is not a weakly prime, because it can be changed into another prime (161639957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80819988 + 80819989.

It is an arithmetic number, because the mean of its divisors is an integer number (80819989).

Almost surely, 2^161639977 is an apocalyptic number.

It is an amenable number.

161639977 is a deficient number, since it is larger than the sum of its proper divisors (1).

161639977 is an equidigital number, since it uses as much as digits as its factorization.

161639977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 428652, while the sum is 49.

The square root of 161639977 is about 12713.7711557193. The cubic root of 161639977 is about 544.7320479522.

The spelling of 161639977 in words is "one hundred sixty-one million, six hundred thirty-nine thousand, nine hundred seventy-seven".