21454785517 has 12 divisors (see below), whose sum is σ = 23591026620. Its totient is φ = 19497325760.

The previous prime is 21454785511. The next prime is 21454785551. The reversal of 21454785517 is 71558745412.

It can be written as a sum of positive squares in 2 ways, for example, as 11370809956 + 10083975561 = 106634^2 + 100419^2 .

It is not a de Polignac number, because 21454785517 - 2³ = 21454785509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21454785511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 321513 + ... + 382465.

It is an arithmetic number, because the mean of its divisors is an integer number (1965918885).

Almost surely, 2^21454785517 is an apocalyptic number.

It is an amenable number.

21454785517 is a deficient number, since it is larger than the sum of its proper divisors (2136241103).

21454785517 is a wasteful number, since it uses less digits than its factorization.

21454785517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63884 (or 63873 counting only the distinct ones).

The product of its digits is 1568000, while the sum is 49.

The spelling of 21454785517 in words is "twenty-one billion, four hundred fifty-four million, seven hundred eighty-five thousand, five hundred seventeen".