21540223540 has 48 divisors (see below), whose sum is σ = 49835326464. Its totient is φ = 7755248000.

The previous prime is 21540223517. The next prime is 21540223571. The reversal of 21540223540 is 4532204512.

It is a junction number, because it is equal to n+sod(n) for n = 21540223499 and 21540223508.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 462484 + ... + 506923.

It is an arithmetic number, because the mean of its divisors is an integer number (1038235968).

Almost surely, 2^21540223540 is an apocalyptic number.

21540223540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21540223540 is an abundant number, since it is smaller than the sum of its proper divisors (28295102924).

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

21540223540 is a wasteful number, since it uses less digits than its factorization.

21540223540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 969528 (or 969526 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 28.

The spelling of 21540223540 in words is "twenty-one billion, five hundred forty million, two hundred twenty-three thousand, five hundred forty".