165661631 has 2 divisors, whose sum is σ = 165661632. Its totient is φ = 165661630.

The previous prime is 165661621. The next prime is 165661637. The reversal of 165661631 is 136166561.

It is a strong prime.

It is an emirp because it is prime and its reverse (136166561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165661631 - 2⁶ = 165661567 is a prime.

It is a super-2 number, since 2×165661631² = 54887551971160322, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 165661591 and 165661600.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165661637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82830815 + 82830816.

It is an arithmetic number, because the mean of its divisors is an integer number (82830816).

Almost surely, 2^165661631 is an apocalyptic number.

165661631 is a deficient number, since it is larger than the sum of its proper divisors (1).

165661631 is an equidigital number, since it uses as much as digits as its factorization.

165661631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 35.

The square root of 165661631 is about 12870.9607644496. The cubic root of 165661631 is about 549.2127922748.

The spelling of 165661631 in words is "one hundred sixty-five million, six hundred sixty-one thousand, six hundred thirty-one".