165637961 has 2 divisors, whose sum is σ = 165637962. Its totient is φ = 165637960.

The previous prime is 165637943. The next prime is 165637963. The reversal of 165637961 is 169736561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 126337600 + 39300361 = 11240^2 + 6269^2 .

It is a cyclic number.

It is not a de Polignac number, because 165637961 - 2¹⁸ = 165375817 is a prime.

Together with 165637963, 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 (165637963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82818980 + 82818981.

It is an arithmetic number, because the mean of its divisors is an integer number (82818981).

Almost surely, 2^165637961 is an apocalyptic number.

It is an amenable number.

165637961 is a deficient number, since it is larger than the sum of its proper divisors (1).

165637961 is an equidigital number, since it uses as much as digits as its factorization.

165637961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204120, while the sum is 44.

The square root of 165637961 is about 12870.0412198252. The cubic root of 165637961 is about 549.1866335602.

The spelling of 165637961 in words is "one hundred sixty-five million, six hundred thirty-seven thousand, nine hundred sixty-one".