161961971 has 2 divisors, whose sum is σ = 161961972. Its totient is φ = 161961970.

The previous prime is 161961923. The next prime is 161961973. The reversal of 161961971 is 179169161.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 161961971 - 2¹⁸ = 161699827 is a prime.

Together with 161961973, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (161961973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80980985 + 80980986.

It is an arithmetic number, because the mean of its divisors is an integer number (80980986).

Almost surely, 2^161961971 is an apocalyptic number.

161961971 is a deficient number, since it is larger than the sum of its proper divisors (1).

161961971 is an equidigital number, since it uses as much as digits as its factorization.

161961971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20412, while the sum is 41.

The square root of 161961971 is about 12726.4280534642. The cubic root of 161961971 is about 545.0935181663.

The spelling of 161961971 in words is "one hundred sixty-one million, nine hundred sixty-one thousand, nine hundred seventy-one".