21456515740 has 48 divisors (see below), whose sum is σ = 49182142464. Its totient is φ = 7798049600.

The previous prime is 21456515723. The next prime is 21456515749. The reversal of 21456515740 is 4751565412.

It is a junction number, because it is equal to n+sod(n) for n = 21456515693 and 21456515702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456515749) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 385557 + ... + 437683.

It is an arithmetic number, because the mean of its divisors is an integer number (1024627968).

Almost surely, 2^21456515740 is an apocalyptic number.

21456515740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21456515740 is an abundant number, since it is smaller than the sum of its proper divisors (27725626724).

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

21456515740 is a wasteful number, since it uses less digits than its factorization.

21456515740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54018 (or 54016 counting only the distinct ones).

The product of its (nonzero) digits is 168000, while the sum is 40.

The spelling of 21456515740 in words is "twenty-one billion, four hundred fifty-six million, five hundred fifteen thousand, seven hundred forty".