2157194988 has 72 divisors (see below), whose sum is σ = 5955165216. Its totient is φ = 654393600.

The previous prime is 2157194987. The next prime is 2157194999. The reversal of 2157194988 is 8894917512.

It is a happy number.

2157194988 is a `hidden beast` number, since 21 + 571 + 9 + 49 + 8 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (2157194987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 768 + ... + 65688.

It is an arithmetic number, because the mean of its divisors is an integer number (82710628).

Almost surely, 2^2157194988 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2157194988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2977582608).

2157194988 is an abundant number, since it is smaller than the sum of its proper divisors (3797970228).

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

2157194988 is a wasteful number, since it uses less digits than its factorization.

2157194988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65015 (or 65010 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 54.

The square root of 2157194988 is about 46445.6132266547. The cubic root of 2157194988 is about 1292.1010146684.

The spelling of 2157194988 in words is "two billion, one hundred fifty-seven million, one hundred ninety-four thousand, nine hundred eighty-eight".