21761431 has 2 divisors, whose sum is σ = 21761432. Its totient is φ = 21761430.

The previous prime is 21761393. The next prime is 21761437. The reversal of 21761431 is 13416712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21761431 - 2⁷ = 21761303 is a prime.

It is a super-2 number, since 2×21761431² = 947119758335522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21761396 and 21761405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21761437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10880715 + 10880716.

It is an arithmetic number, because the mean of its divisors is an integer number (10880716).

Almost surely, 2^21761431 is an apocalyptic number.

21761431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21761431 is an equidigital number, since it uses as much as digits as its factorization.

21761431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 25.

The square root of 21761431 is about 4664.9148974017. The cubic root of 21761431 is about 279.1874016628.

The spelling of 21761431 in words is "twenty-one million, seven hundred sixty-one thousand, four hundred thirty-one".