21909743 has 2 divisors, whose sum is σ = 21909744. Its totient is φ = 21909742.

The previous prime is 21909733. The next prime is 21909799. The reversal of 21909743 is 34790912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21909743 - 2¹² = 21905647 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21909733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10954871 + 10954872.

It is an arithmetic number, because the mean of its divisors is an integer number (10954872).

Almost surely, 2^21909743 is an apocalyptic number.

21909743 is a deficient number, since it is larger than the sum of its proper divisors (1).

21909743 is an equidigital number, since it uses as much as digits as its factorization.

21909743 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 21909743 is about 4680.7844428044. The cubic root of 21909743 is about 279.8202204781.

The spelling of 21909743 in words is "twenty-one million, nine hundred nine thousand, seven hundred forty-three".