21591000919 has 2 divisors, whose sum is σ = 21591000920. Its totient is φ = 21591000918.

The previous prime is 21591000901. The next prime is 21591000967. The reversal of 21591000919 is 91900019512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21591000919 is a prime.

It is a super-2 number, since 2×21591000919² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21591000419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10795500459 + 10795500460.

It is an arithmetic number, because the mean of its divisors is an integer number (10795500460).

Almost surely, 2^21591000919 is an apocalyptic number.

21591000919 is a deficient number, since it is larger than the sum of its proper divisors (1).

21591000919 is an equidigital number, since it uses as much as digits as its factorization.

21591000919 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7290, while the sum is 37.

The spelling of 21591000919 in words is "twenty-one billion, five hundred ninety-one million, nine hundred nineteen", and thus it is an aban number.