21326431 has 8 divisors (see below), whose sum is σ = 24523904. Its totient is φ = 18166680.

The previous prime is 21326429. The next prime is 21326441. The reversal of 21326431 is 13462312.

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

It is not a de Polignac number, because 21326431 - 2¹ = 21326429 is a prime.

It is a super-2 number, since 2×21326431² = 909633318395522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21326411) 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, 8205 + ... + 10486.

It is an arithmetic number, because the mean of its divisors is an integer number (3065488).

Almost surely, 2^21326431 is an apocalyptic number.

21326431 is a deficient number, since it is larger than the sum of its proper divisors (3197473).

21326431 is a wasteful number, since it uses less digits than its factorization.

21326431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18861.

The product of its digits is 864, while the sum is 22.

The square root of 21326431 is about 4618.0548935672. The cubic root of 21326431 is about 277.3145951973.

Adding to 21326431 its reverse (13462312), we get a palindrome (34788743).

The spelling of 21326431 in words is "twenty-one million, three hundred twenty-six thousand, four hundred thirty-one".