21531479640 has 256 divisors, whose sum is σ = 72760343040. Its totient is φ = 5051904000.

The previous prime is 21531479617. The next prime is 21531479657. The reversal of 21531479640 is 4697413512.

It is a junction number, because it is equal to n+sod(n) for n = 21531479592 and 21531479601.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 7088202 + ... + 7091238.

It is an arithmetic number, because the mean of its divisors is an integer number (284220090).

Almost surely, 2^21531479640 is an apocalyptic number.

21531479640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21531479640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36380171520).

21531479640 is an abundant number, since it is smaller than the sum of its proper divisors (51228863400).

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

21531479640 is a wasteful number, since it uses less digits than its factorization.

21531479640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3234 (or 3230 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 42.

The spelling of 21531479640 in words is "twenty-one billion, five hundred thirty-one million, four hundred seventy-nine thousand, six hundred forty".