2157721563 has 32 divisors (see below), whose sum is σ = 3094350336. Its totient is φ = 1333905408.

The previous prime is 2157721561. The next prime is 2157721571. The reversal of 2157721563 is 3651277512.

It is a happy number.

2157721563 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2157721563 - 2¹ = 2157721561 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2157721561) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 782395 + ... + 785147.

It is an arithmetic number, because the mean of its divisors is an integer number (96698448).

Almost surely, 2^2157721563 is an apocalyptic number.

2157721563 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

2157721563 is a deficient number, since it is larger than the sum of its proper divisors (936628773).

2157721563 is a wasteful number, since it uses less digits than its factorization.

2157721563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3123.

The product of its digits is 88200, while the sum is 39.

The square root of 2157721563 is about 46451.2816077232. The cubic root of 2157721563 is about 1292.2061408070.

The spelling of 2157721563 in words is "two billion, one hundred fifty-seven million, seven hundred twenty-one thousand, five hundred sixty-three".