21854431 has 2 divisors, whose sum is σ = 21854432. Its totient is φ = 21854430.

The previous prime is 21854423. The next prime is 21854461. The reversal of 21854431 is 13445812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21854431 - 2³ = 21854423 is a prime.

It is a super-2 number, since 2×21854431² = 955232308667522, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21854431.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21854461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10927215 + 10927216.

It is an arithmetic number, because the mean of its divisors is an integer number (10927216).

Almost surely, 2^21854431 is an apocalyptic number.

21854431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21854431 is an equidigital number, since it uses as much as digits as its factorization.

21854431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3840, while the sum is 28.

The square root of 21854431 is about 4674.8722977211. The cubic root of 21854431 is about 279.5845496964.

The spelling of 21854431 in words is "twenty-one million, eight hundred fifty-four thousand, four hundred thirty-one".