2156849991 has 32 divisors (see below), whose sum is σ = 3288526080. Its totient is φ = 1396126368.

The previous prime is 2156849987. The next prime is 2156850023. The reversal of 2156849991 is 1999486512.

2156849991 is a `hidden beast` number, since 2 + 1 + 5 + 68 + 499 + 91 = 666.

It is not a de Polignac number, because 2156849991 - 2² = 2156849987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2156849951) 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, 544480 + ... + 548426.

It is an arithmetic number, because the mean of its divisors is an integer number (102766440).

Almost surely, 2^2156849991 is an apocalyptic number.

2156849991 is a deficient number, since it is larger than the sum of its proper divisors (1131676089).

2156849991 is a wasteful number, since it uses less digits than its factorization.

2156849991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4540 (or 4534 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 54.

The square root of 2156849991 is about 46441.8990890769. The cubic root of 2156849991 is about 1292.0321297288.

The spelling of 2156849991 in words is "two billion, one hundred fifty-six million, eight hundred forty-nine thousand, nine hundred ninety-one".