21974721 has 8 divisors (see below), whose sum is σ = 30310080. Its totient is φ = 14144592.

The previous prime is 21974717. The next prime is 21974731. The reversal of 21974721 is 12747912.

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

It is not a de Polignac number, because 21974721 - 2² = 21974717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21974731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126205 + ... + 126378.

It is an arithmetic number, because the mean of its divisors is an integer number (3788760).

Almost surely, 2^21974721 is an apocalyptic number.

It is an amenable number.

21974721 is a deficient number, since it is larger than the sum of its proper divisors (8335359).

21974721 is a wasteful number, since it uses less digits than its factorization.

21974721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252615.

The product of its digits is 7056, while the sum is 33.

The square root of 21974721 is about 4687.7202348263. The cubic root of 21974721 is about 280.0965695813.

The spelling of 21974721 in words is "twenty-one million, nine hundred seventy-four thousand, seven hundred twenty-one".