21615535344 has 120 divisors (see below), whose sum is σ = 60574841712. Its totient is φ = 6638960640.

The previous prime is 21615535327. The next prime is 21615535351. The reversal of 21615535344 is 44353551612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5197714 + ... + 5201870.

Almost surely, 2^21615535344 is an apocalyptic number.

21615535344 is a gapful number since it is divisible by the number (24) 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 21615535344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30287420856).

21615535344 is an abundant number, since it is smaller than the sum of its proper divisors (38959306368).

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

21615535344 is a wasteful number, since it uses less digits than its factorization.

21615535344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4835 (or 4816 counting only the distinct ones).

The product of its digits is 216000, while the sum is 39.

The spelling of 21615535344 in words is "twenty-one billion, six hundred fifteen million, five hundred thirty-five thousand, three hundred forty-four".