161221572 has 36 divisors (see below), whose sum is σ = 409683456. Its totient is φ = 53456880.

The previous prime is 161221561. The next prime is 161221579. The reversal of 161221572 is 275122161.

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (161221579) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4848 + ... + 18599.

It is an arithmetic number, because the mean of its divisors is an integer number (11380096).

Almost surely, 2^161221572 is an apocalyptic number.

161221572 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

161221572 is an abundant number, since it is smaller than the sum of its proper divisors (248461884).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161221572 is a wasteful number, since it uses less digits than its factorization.

161221572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23648 (or 23643 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 161221572 is about 12697.3056984543. The cubic root of 161221572 is about 544.2616289470.

The spelling of 161221572 in words is "one hundred sixty-one million, two hundred twenty-one thousand, five hundred seventy-two".