21991419 has 10 divisors (see below), whose sum is σ = 32851500. Its totient is φ = 14660892.

The previous prime is 21991397. The next prime is 21991433. The reversal of 21991419 is 91419912.

It is not a de Polignac number, because 21991419 - 2⁸ = 21991163 is a prime.

It is a super-2 number, since 2×21991419² = 967245019267122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21991439) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 135669 + ... + 135830.

It is an arithmetic number, because the mean of its divisors is an integer number (3285150).

Almost surely, 2^21991419 is an apocalyptic number.

21991419 is a deficient number, since it is larger than the sum of its proper divisors (10860081).

21991419 is an equidigital number, since it uses as much as digits as its factorization.

21991419 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271511 (or 271502 counting only the distinct ones).

The product of its digits is 5832, while the sum is 36.

The square root of 21991419 is about 4689.5009329352. The cubic root of 21991419 is about 280.1674975711.

The spelling of 21991419 in words is "twenty-one million, nine hundred ninety-one thousand, four hundred nineteen".