2191978469 has 4 divisors (see below), whose sum is σ = 2196285420. Its totient is φ = 2187671520.

The previous prime is 2191978447. The next prime is 2191978483. The reversal of 2191978469 is 9648791912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1562620900 + 629357569 = 39530^2 + 25087^2 .

It is a cyclic number.

It is not a de Polignac number, because 2191978469 - 2⁸ = 2191978213 is a prime.

It is a super-2 number, since 2×2191978469² = 9609539217119167922, 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 (2191978409) 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, 2152712 + ... + 2153729.

It is an arithmetic number, because the mean of its divisors is an integer number (549071355).

Almost surely, 2^2191978469 is an apocalyptic number.

It is an amenable number.

2191978469 is a deficient number, since it is larger than the sum of its proper divisors (4306951).

2191978469 is an equidigital number, since it uses as much as digits as its factorization.

2191978469 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4306950.

The product of its digits is 1959552, while the sum is 56.

The square root of 2191978469 is about 46818.5697026297. The cubic root of 2191978469 is about 1299.0088044075.

The spelling of 2191978469 in words is "two billion, one hundred ninety-one million, nine hundred seventy-eight thousand, four hundred sixty-nine".