21974647 has 4 divisors (see below), whose sum is σ = 22510656. Its totient is φ = 21438640.

The previous prime is 21974627. The next prime is 21974651. The reversal of 21974647 is 74647912.

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 21974647 - 2¹⁵ = 21941879 is a prime.

It is a super-2 number, since 2×21974647² = 965770221549218, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21974627) 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, 267943 + ... + 268024.

It is an arithmetic number, because the mean of its divisors is an integer number (5627664).

Almost surely, 2^21974647 is an apocalyptic number.

21974647 is a deficient number, since it is larger than the sum of its proper divisors (536009).

21974647 is an equidigital number, since it uses as much as digits as its factorization.

21974647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536008.

The product of its digits is 84672, while the sum is 40.

The square root of 21974647 is about 4687.7123418572. The cubic root of 21974647 is about 280.0962551720.

The spelling of 21974647 in words is "twenty-one million, nine hundred seventy-four thousand, six hundred forty-seven".