21519791 has 2 divisors, whose sum is σ = 21519792. Its totient is φ = 21519790.

The previous prime is 21519727. The next prime is 21519803. The reversal of 21519791 is 19791512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21519791 - 2⁶ = 21519727 is a prime.

It is a Sophie Germain 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 (21519721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10759895 + 10759896.

It is an arithmetic number, because the mean of its divisors is an integer number (10759896).

Almost surely, 2^21519791 is an apocalyptic number.

21519791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21519791 is an equidigital number, since it uses as much as digits as its factorization.

21519791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5670, while the sum is 35.

The square root of 21519791 is about 4638.9428752680. The cubic root of 21519791 is about 278.1501828142.

The spelling of 21519791 in words is "twenty-one million, five hundred nineteen thousand, seven hundred ninety-one".