161977969 has 2 divisors, whose sum is σ = 161977970. Its totient is φ = 161977968.

The previous prime is 161977919. The next prime is 161977987. The reversal of 161977969 is 969779161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 151167025 + 10810944 = 12295^2 + 3288^2 .

It is a cyclic number.

It is not a de Polignac number, because 161977969 - 2⁹ = 161977457 is a prime.

It is a super-2 number, since 2×161977969² = 52473724882729922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161977919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80988984 + 80988985.

It is an arithmetic number, because the mean of its divisors is an integer number (80988985).

Almost surely, 2^161977969 is an apocalyptic number.

It is an amenable number.

161977969 is a deficient number, since it is larger than the sum of its proper divisors (1).

161977969 is an equidigital number, since it uses as much as digits as its factorization.

161977969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1285956, while the sum is 55.

The square root of 161977969 is about 12727.0565725151. The cubic root of 161977969 is about 545.1114650110. Note that the first 3 decimals are identical.

The spelling of 161977969 in words is "one hundred sixty-one million, nine hundred seventy-seven thousand, nine hundred sixty-nine".