181957617820 has 36 divisors (see below), whose sum is σ = 416862855864. Its totient is φ = 66164105760.

The previous prime is 181957617797. The next prime is 181957617827. The reversal of 181957617820 is 28716759181.

It is a Harshad number since it is a multiple of its sum of digits (55).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181957617827) 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, 6312601 + ... + 6341359.

It is an arithmetic number, because the mean of its divisors is an integer number (11579523774).

Almost surely, 2^181957617820 is an apocalyptic number.

181957617820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181957617820 is an abundant number, since it is smaller than the sum of its proper divisors (234905238044).

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

181957617820 is an frugal number, since it uses more digits than its factorization.

181957617820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57538 (or 28777 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 55.

Multiplying 181957617820 by its sum of digits (55), we get a square (10007668980100 = 3163490²).

181957617820 divided by its sum of digits (55) gives a square (3308320324 = 57518²).

The spelling of 181957617820 in words is "one hundred eighty-one billion, nine hundred fifty-seven million, six hundred seventeen thousand, eight hundred twenty".