21523431340 has 48 divisors (see below), whose sum is σ = 46412349984. Its totient is φ = 8379302400.

The previous prime is 21523431337. The next prime is 21523431373. The reversal of 21523431340 is 4313432512.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21523431299 and 21523431308.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 314047 + ... + 376393.

It is an arithmetic number, because the mean of its divisors is an integer number (966923958).

Almost surely, 2^21523431340 is an apocalyptic number.

21523431340 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 21523431340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23206174992).

21523431340 is an abundant number, since it is smaller than the sum of its proper divisors (24888918644).

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

21523431340 is a wasteful number, since it uses less digits than its factorization.

21523431340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62818 (or 62816 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 28.

Adding to 21523431340 its reverse (4313432512), we get a palindrome (25836863852).

The spelling of 21523431340 in words is "twenty-one billion, five hundred twenty-three million, four hundred thirty-one thousand, three hundred forty".