21183791 has 2 divisors, whose sum is σ = 21183792. Its totient is φ = 21183790.

The previous prime is 21183787. The next prime is 21183809. The reversal of 21183791 is 19738112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21183791 - 2² = 21183787 is a prime.

It is a super-2 number, since 2×21183791² = 897506002263362, which contains 22 as substring.

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 (21183761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10591895 + 10591896.

It is an arithmetic number, because the mean of its divisors is an integer number (10591896).

Almost surely, 2^21183791 is an apocalyptic number.

21183791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21183791 is an equidigital number, since it uses as much as digits as its factorization.

21183791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 32.

The square root of 21183791 is about 4602.5852517906. The cubic root of 21183791 is about 276.6949467068.

The spelling of 21183791 in words is "twenty-one million, one hundred eighty-three thousand, seven hundred ninety-one".