21924991 has 8 divisors (see below), whose sum is σ = 23958864. Its totient is φ = 19897920.

The previous prime is 21924971. The next prime is 21924997. The reversal of 21924991 is 19942912.

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

It is a cyclic number.

It is not a de Polignac number, because 21924991 - 2²¹ = 19827839 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21924991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21924997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7011 + ... + 9643.

It is an arithmetic number, because the mean of its divisors is an integer number (2994858).

Almost surely, 2^21924991 is an apocalyptic number.

21924991 is a deficient number, since it is larger than the sum of its proper divisors (2033873).

21924991 is a wasteful number, since it uses less digits than its factorization.

21924991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3401.

The product of its digits is 11664, while the sum is 37.

The square root of 21924991 is about 4682.4129463344. The cubic root of 21924991 is about 279.8851186881.

The spelling of 21924991 in words is "twenty-one million, nine hundred twenty-four thousand, nine hundred ninety-one".