21353791 has 2 divisors, whose sum is σ = 21353792. Its totient is φ = 21353790.

The previous prime is 21353767. The next prime is 21353797. The reversal of 21353791 is 19735312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21353791 - 2⁹ = 21353279 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21353797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10676895 + 10676896.

It is an arithmetic number, because the mean of its divisors is an integer number (10676896).

Almost surely, 2^21353791 is an apocalyptic number.

21353791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21353791 is an equidigital number, since it uses as much as digits as its factorization.

21353791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5670, while the sum is 31.

The square root of 21353791 is about 4621.0162302247. The cubic root of 21353791 is about 277.4331348786.

The spelling of 21353791 in words is "twenty-one million, three hundred fifty-three thousand, seven hundred ninety-one".