2156021900 has 72 divisors (see below), whose sum is σ = 4808692224. Its totient is φ = 838566400.

The previous prime is 2156021839. The next prime is 2156021921. The reversal of 2156021900 is 91206512.

It is a super-2 number, since 2×2156021900² = 9296860866559220000, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 2156021900.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1569614 + ... + 1570986.

It is an arithmetic number, because the mean of its divisors is an integer number (66787392).

Almost surely, 2^2156021900 is an apocalyptic number.

2156021900 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 2156021900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2404346112).

2156021900 is an abundant number, since it is smaller than the sum of its proper divisors (2652670324).

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

2156021900 is a wasteful number, since it uses less digits than its factorization.

2156021900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1811 (or 1804 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 2156021900 is about 46432.9828893213. The cubic root of 2156021900 is about 1291.8667562847.

The spelling of 2156021900 in words is "two billion, one hundred fifty-six million, twenty-one thousand, nine hundred".