18161772220 has 24 divisors (see below), whose sum is σ = 39370036608. Its totient is φ = 7030363200.

The previous prime is 18161772217. The next prime is 18161772253. The reversal of 18161772220 is 2227716181.

It is a self number, because there is not a number n which added to its sum of digits gives 18161772220.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 14645971 + ... + 14647210.

It is an arithmetic number, because the mean of its divisors is an integer number (1640418192).

Almost surely, 2^18161772220 is an apocalyptic number.

18161772220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18161772220 is an abundant number, since it is smaller than the sum of its proper divisors (21208264388).

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

18161772220 is a wasteful number, since it uses less digits than its factorization.

18161772220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29293221 (or 29293219 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 37.

The spelling of 18161772220 in words is "eighteen billion, one hundred sixty-one million, seven hundred seventy-two thousand, two hundred twenty".