2156297640 has 128 divisors (see below), whose sum is σ = 7458773760. Its totient is φ = 488484864.

The previous prime is 2156297573. The next prime is 2156297657. The reversal of 2156297640 is 467926512.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 2156297592 and 2156297601.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 83562 + ... + 106278.

It is an arithmetic number, because the mean of its divisors is an integer number (58271670).

Almost surely, 2^2156297640 is an apocalyptic number.

2156297640 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 2156297640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3729386880).

2156297640 is an abundant number, since it is smaller than the sum of its proper divisors (5302476120).

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

2156297640 is a wasteful number, since it uses less digits than its factorization.

2156297640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22851 (or 22847 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 42.

The square root of 2156297640 is about 46435.9520199597. The cubic root of 2156297640 is about 1291.9218274869.

The spelling of 2156297640 in words is "two billion, one hundred fifty-six million, two hundred ninety-seven thousand, six hundred forty".