21790431 has 16 divisors (see below), whose sum is σ = 34765920. Its totient is φ = 13409280.

The previous prime is 21790429. The next prime is 21790441. The reversal of 21790431 is 13409712.

It is not a de Polignac number, because 21790431 - 2¹ = 21790429 is a prime.

It is a super-2 number, since 2×21790431² = 949645766331522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21790395 and 21790404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21790421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30690 + ... + 31391.

It is an arithmetic number, because the mean of its divisors is an integer number (2172870).

Almost surely, 2^21790431 is an apocalyptic number.

21790431 is a deficient number, since it is larger than the sum of its proper divisors (12975489).

21790431 is a wasteful number, since it uses less digits than its factorization.

21790431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62103 (or 62097 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21790431 is about 4668.0221721838. The cubic root of 21790431 is about 279.3113647236.

The spelling of 21790431 in words is "twenty-one million, seven hundred ninety thousand, four hundred thirty-one".