21282391 has 8 divisors (see below), whose sum is σ = 23096304. Its totient is φ = 19493760.

The previous prime is 21282389. The next prime is 21282397. The reversal of 21282391 is 19328212.

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

It is not a de Polignac number, because 21282391 - 2¹ = 21282389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21282397) 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, 4546 + ... + 7951.

It is an arithmetic number, because the mean of its divisors is an integer number (2887038).

Almost surely, 2^21282391 is an apocalyptic number.

21282391 is a deficient number, since it is larger than the sum of its proper divisors (1813913).

21282391 is a wasteful number, since it uses less digits than its factorization.

21282391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12641.

The product of its digits is 1728, while the sum is 28.

The square root of 21282391 is about 4613.2841880812. The cubic root of 21282391 is about 277.1235747811.

The spelling of 21282391 in words is "twenty-one million, two hundred eighty-two thousand, three hundred ninety-one".