2179047991 has 4 divisors (see below), whose sum is σ = 2273789232. Its totient is φ = 2084306752.

The previous prime is 2179047977. The next prime is 2179048009. The reversal of 2179047991 is 1997409712.

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 2179047991 - 2¹³ = 2179039799 is a prime.

It is a super-2 number, since 2×2179047991² = 9496500294162272162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2179047191) 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, 47370586 + ... + 47370631.

It is an arithmetic number, because the mean of its divisors is an integer number (568447308).

Almost surely, 2^2179047991 is an apocalyptic number.

2179047991 is a deficient number, since it is larger than the sum of its proper divisors (94741241).

2179047991 is an equidigital number, since it uses as much as digits as its factorization.

2179047991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94741240.

The product of its (nonzero) digits is 285768, while the sum is 49.

The square root of 2179047991 is about 46680.2741101635. The cubic root of 2179047991 is about 1296.4494815883.

The spelling of 2179047991 in words is "two billion, one hundred seventy-nine million, forty-seven thousand, nine hundred ninety-one".