21222691 has 4 divisors (see below), whose sum is σ = 24254512. Its totient is φ = 18190872.

The previous prime is 21222689. The next prime is 21222697. The reversal of 21222691 is 19622212.

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

It is not a de Polignac number, because 21222691 - 2¹ = 21222689 is a prime.

It is a super-2 number, since 2×21222691² = 900805226562962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21222697) 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, 1515900 + ... + 1515913.

It is an arithmetic number, because the mean of its divisors is an integer number (6063628).

Almost surely, 2^21222691 is an apocalyptic number.

21222691 is a deficient number, since it is larger than the sum of its proper divisors (3031821).

21222691 is an equidigital number, since it uses as much as digits as its factorization.

21222691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3031820.

The product of its digits is 864, while the sum is 25.

The square root of 21222691 is about 4606.8091994351. The cubic root of 21222691 is about 276.8642090107.

The spelling of 21222691 in words is "twenty-one million, two hundred twenty-two thousand, six hundred ninety-one".