21621532634540 has 48 divisors (see below), whose sum is σ = 45877011223680. Its totient is φ = 8558830828800.

The previous prime is 21621532634519. The next prime is 21621532634593. The reversal of 21621532634540 is 4543623512612.

It is a junction number, because it is equal to n+sod(n) for n = 21621532634491 and 21621532634500.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1573046 + ... + 6761474.

It is an arithmetic number, because the mean of its divisors is an integer number (955771067160).

Almost surely, 2^{21621532634540} is an apocalyptic number.

21621532634540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21621532634540 is an abundant number, since it is smaller than the sum of its proper divisors (24255478589140).

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

21621532634540 is a wasteful number, since it uses less digits than its factorization.

21621532634540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5190602 (or 5190600 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 44.

The spelling of 21621532634540 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred thirty-two million, six hundred thirty-four thousand, five hundred forty".