2157510991 has 4 divisors (see below), whose sum is σ = 2159675992. Its totient is φ = 2155345992.

The previous prime is 2157510977. The next prime is 2157511001. The reversal of 2157510991 is 1990157512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2157510991 - 2⁷ = 2157510863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157510931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1081005 + ... + 1082998.

It is an arithmetic number, because the mean of its divisors is an integer number (539918998).

Almost surely, 2^2157510991 is an apocalyptic number.

2157510991 is a deficient number, since it is larger than the sum of its proper divisors (2165001).

2157510991 is an equidigital number, since it uses as much as digits as its factorization.

2157510991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2165000.

The product of its (nonzero) digits is 28350, while the sum is 40.

The square root of 2157510991 is about 46449.0149626448. The cubic root of 2157510991 is about 1292.1641039832.

The spelling of 2157510991 in words is "two billion, one hundred fifty-seven million, five hundred ten thousand, nine hundred ninety-one".