21443431 has 2 divisors, whose sum is σ = 21443432. Its totient is φ = 21443430.

The previous prime is 21443363. The next prime is 21443437. The reversal of 21443431 is 13434412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21443431 - 2¹¹ = 21441383 is a prime.

It is a super-2 number, since 2×21443431² = 919641466103522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21443437) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721715 + 10721716.

It is an arithmetic number, because the mean of its divisors is an integer number (10721716).

Almost surely, 2^21443431 is an apocalyptic number.

21443431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21443431 is an equidigital number, since it uses as much as digits as its factorization.

21443431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 22.

The square root of 21443431 is about 4630.7052378660. The cubic root of 21443431 is about 277.8208004414.

Adding to 21443431 its reverse (13434412), we get a palindrome (34877843).

The spelling of 21443431 in words is "twenty-one million, four hundred forty-three thousand, four hundred thirty-one".