21791515540 has 48 divisors (see below), whose sum is σ = 46419645888. Its totient is φ = 8591857664.

The previous prime is 21791515519. The next prime is 21791515541. The reversal of 21791515540 is 4551519712.

It is a super-2 number, since 2×21791515540² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21791515493 and 21791515502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21791515541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 720564 + ... + 750196.

It is an arithmetic number, because the mean of its divisors is an integer number (967075956).

Almost surely, 2^21791515540 is an apocalyptic number.

21791515540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21791515540 is an abundant number, since it is smaller than the sum of its proper divisors (24628130348).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21791515540 is a wasteful number, since it uses less digits than its factorization.

21791515540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30168 (or 30166 counting only the distinct ones).

The product of its (nonzero) digits is 63000, while the sum is 40.

The spelling of 21791515540 in words is "twenty-one billion, seven hundred ninety-one million, five hundred fifteen thousand, five hundred forty".