161921939 has 2 divisors, whose sum is σ = 161921940. Its totient is φ = 161921938.

The previous prime is 161921869. The next prime is 161921951. The reversal of 161921939 is 939129161.

It is a strong prime.

It is an emirp because it is prime and its reverse (939129161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161921939 - 2²⁴ = 145144723 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 161921896 and 161921905.

It is not a weakly prime, because it can be changed into another prime (161926939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80960969 + 80960970.

It is an arithmetic number, because the mean of its divisors is an integer number (80960970).

Almost surely, 2^161921939 is an apocalyptic number.

161921939 is a deficient number, since it is larger than the sum of its proper divisors (1).

161921939 is an equidigital number, since it uses as much as digits as its factorization.

161921939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26244, while the sum is 41.

The square root of 161921939 is about 12724.8551661699. The cubic root of 161921939 is about 545.0486043682.

The spelling of 161921939 in words is "one hundred sixty-one million, nine hundred twenty-one thousand, nine hundred thirty-nine".