21648495491 has 16 divisors (see below), whose sum is σ = 25118764800. Its totient is φ = 18272818080.

The previous prime is 21648495461. The next prime is 21648495493. The reversal of 21648495491 is 19459484612.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21648495491 is a prime.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21648495493) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1916801 + ... + 1928061.

It is an arithmetic number, because the mean of its divisors is an integer number (1569922800).

Almost surely, 2^21648495491 is an apocalyptic number.

21648495491 is a deficient number, since it is larger than the sum of its proper divisors (3470269309).

21648495491 is a wasteful number, since it uses less digits than its factorization.

21648495491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15434.

The product of its digits is 2488320, while the sum is 53.

The spelling of 21648495491 in words is "twenty-one billion, six hundred forty-eight million, four hundred ninety-five thousand, four hundred ninety-one".