2155185720 has 192 divisors, whose sum is σ = 7298553600. Its totient is φ = 550932480.

The previous prime is 2155185679. The next prime is 2155185763. The reversal of 2155185720 is 275815512.

2155185720 is a `hidden beast` number, since 2 + 1 + 551 + 85 + 7 + 20 = 666.

It is a super-4 number, since 4×2155185720⁴ (a number of 38 digits) contains 4444 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1260226 + ... + 1261934.

It is an arithmetic number, because the mean of its divisors is an integer number (38013300).

Almost surely, 2^2155185720 is an apocalyptic number.

2155185720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2155185720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3649276800).

2155185720 is an abundant number, since it is smaller than the sum of its proper divisors (5143367880).

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

2155185720 is a wasteful number, since it uses less digits than its factorization.

2155185720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1870 (or 1863 counting only the distinct ones).

The product of its (nonzero) digits is 28000, while the sum is 36.

The square root of 2155185720 is about 46423.9778562760. The cubic root of 2155185720 is about 1291.6997244586.

The spelling of 2155185720 in words is "two billion, one hundred fifty-five million, one hundred eighty-five thousand, seven hundred twenty".