21723641621540 has 48 divisors (see below), whose sum is σ = 45683684145792. Its totient is φ = 8677267312896.

The previous prime is 21723641621519. The next prime is 21723641621573. The reversal of 21723641621540 is 4512614632712.

It is a super-2 number, since 2×21723641621540² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21723641621491 and 21723641621500.

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, 42708392 + ... + 43214048.

It is an arithmetic number, because the mean of its divisors is an integer number (951743419704).

Almost surely, 2^{21723641621540} is an apocalyptic number.

21723641621540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21723641621540 is an abundant number, since it is smaller than the sum of its proper divisors (23960042524252).

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

21723641621540 is a wasteful number, since it uses less digits than its factorization.

21723641621540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508676 (or 508674 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 44.

The spelling of 21723641621540 in words is "twenty-one trillion, seven hundred twenty-three billion, six hundred forty-one million, six hundred twenty-one thousand, five hundred forty".