21793491 has 12 divisors (see below), whose sum is σ = 31520632. Its totient is φ = 14510016.

The previous prime is 21793487. The next prime is 21793501. The reversal of 21793491 is 19439712.

It is not a de Polignac number, because 21793491 - 2² = 21793487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21793451) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10740 + ... + 12606.

Almost surely, 2^21793491 is an apocalyptic number.

21793491 is a deficient number, since it is larger than the sum of its proper divisors (9727141).

21793491 is a wasteful number, since it uses less digits than its factorization.

21793491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3170 (or 3167 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 21793491 is about 4668.3499226172. The cubic root of 21793491 is about 279.3244385475.

The spelling of 21793491 in words is "twenty-one million, seven hundred ninety-three thousand, four hundred ninety-one".