161722751 has 4 divisors (see below), whose sum is σ = 171235872. Its totient is φ = 152209632.

The previous prime is 161722739. The next prime is 161722787. The reversal of 161722751 is 157227161.

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

It is a cyclic number.

It is not a de Polignac number, because 161722751 - 2²² = 157528447 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 (161722721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4756535 + ... + 4756568.

It is an arithmetic number, because the mean of its divisors is an integer number (42808968).

Almost surely, 2^161722751 is an apocalyptic number.

161722751 is a deficient number, since it is larger than the sum of its proper divisors (9513121).

161722751 is an equidigital number, since it uses as much as digits as its factorization.

161722751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9513120.

The product of its digits is 5880, while the sum is 32.

The square root of 161722751 is about 12717.0260281247. The cubic root of 161722751 is about 544.8250157871.

The spelling of 161722751 in words is "one hundred sixty-one million, seven hundred twenty-two thousand, seven hundred fifty-one".