161722973 has 4 divisors (see below), whose sum is σ = 163206780. Its totient is φ = 160239168.

The previous prime is 161722969. The next prime is 161722987. The reversal of 161722973 is 379227161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 142730809 + 18992164 = 11947^2 + 4358^2 .

It is a cyclic number.

It is not a de Polignac number, because 161722973 - 2² = 161722969 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161722933) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 741740 + ... + 741957.

It is an arithmetic number, because the mean of its divisors is an integer number (40801695).

Almost surely, 2^161722973 is an apocalyptic number.

It is an amenable number.

161722973 is a deficient number, since it is larger than the sum of its proper divisors (1483807).

161722973 is a wasteful number, since it uses less digits than its factorization.

161722973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1483806.

The product of its digits is 31752, while the sum is 38.

The square root of 161722973 is about 12717.0347565775. The cubic root of 161722973 is about 544.8252650844.

The spelling of 161722973 in words is "one hundred sixty-one million, seven hundred twenty-two thousand, nine hundred seventy-three".