2157688340 has 24 divisors (see below), whose sum is σ = 4605429192. Its totient is φ = 848926080.

The previous prime is 2157688339. The next prime is 2157688387. The reversal of 2157688340 is 438867512.

It can be written as a sum of positive squares in 4 ways, for example, as 643204 + 2157045136 = 802^2 + 46444^2 .

It is a junction number, because it is equal to n+sod(n) for n = 2157688291 and 2157688300.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 883079 + ... + 885518.

It is an arithmetic number, because the mean of its divisors is an integer number (191892883).

Almost surely, 2^2157688340 is an apocalyptic number.

2157688340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2157688340 is an abundant number, since it is smaller than the sum of its proper divisors (2447740852).

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

2157688340 is a wasteful number, since it uses less digits than its factorization.

2157688340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1768667 (or 1768665 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 44.

The square root of 2157688340 is about 46450.9239951155. The cubic root of 2157688340 is about 1292.1995086283.

The spelling of 2157688340 in words is "two billion, one hundred fifty-seven million, six hundred eighty-eight thousand, three hundred forty".