2156021899 has 4 divisors (see below), whose sum is σ = 2156348664. Its totient is φ = 2155695136.

The previous prime is 2156021839. The next prime is 2156021921. The reversal of 2156021899 is 9981206512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2156021899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2156021809) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 153277 + ... + 166750.

It is an arithmetic number, because the mean of its divisors is an integer number (539087166).

Almost surely, 2^2156021899 is an apocalyptic number.

2156021899 is a deficient number, since it is larger than the sum of its proper divisors (326765).

2156021899 is an equidigital number, since it uses as much as digits as its factorization.

2156021899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 326764.

The product of its (nonzero) digits is 77760, while the sum is 43.

The square root of 2156021899 is about 46432.9828785530. The cubic root of 2156021899 is about 1291.8667560849.

The spelling of 2156021899 in words is "two billion, one hundred fifty-six million, twenty-one thousand, eight hundred ninety-nine".