21340431 has 48 divisors (see below), whose sum is σ = 37273600. Its totient is φ = 11748240.

The previous prime is 21340421. The next prime is 21340441. The reversal of 21340431 is 13404312.

It is an interprime number because it is at equal distance from previous prime (21340421) and next prime (21340441).

It is not a de Polignac number, because 21340431 - 2⁶ = 21340367 is a prime.

It is a super-2 number, since 2×21340431² = 910827990531522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21340411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 95586 + ... + 95808.

Almost surely, 2^21340431 is an apocalyptic number.

21340431 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21340431 is a deficient number, since it is larger than the sum of its proper divisors (15933169).

21340431 is a wasteful number, since it uses less digits than its factorization.

21340431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281 (or 264 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21340431 is about 4619.5704345751. The cubic root of 21340431 is about 277.3752641248.

Adding to 21340431 its reverse (13404312), we get a palindrome (34744743).

It can be divided in two parts, 2 and 1340431, that multiplied together give a palindrome (2680862).

The spelling of 21340431 in words is "twenty-one million, three hundred forty thousand, four hundred thirty-one".