21999291 has 8 divisors (see below), whose sum is σ = 29375040. Its totient is φ = 14644872.

The previous prime is 21999281. The next prime is 21999301. The reversal of 21999291 is 19299912.

It is an interprime number because it is at equal distance from previous prime (21999281) and next prime (21999301).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21999291 - 2⁷ = 21999163 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21999221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2745 + ... + 7178.

It is an arithmetic number, because the mean of its divisors is an integer number (3671880).

Almost surely, 2^21999291 is an apocalyptic number.

21999291 is a deficient number, since it is larger than the sum of its proper divisors (7375749).

21999291 is an equidigital number, since it uses as much as digits as its factorization.

21999291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10665.

The product of its digits is 26244, while the sum is 42.

The square root of 21999291 is about 4690.3401795605. The cubic root of 21999291 is about 280.2009229637.

The spelling of 21999291 in words is "twenty-one million, nine hundred ninety-nine thousand, two hundred ninety-one".