21534000000 has 448 divisors, whose sum is σ = 74188112880. Its totient is φ = 5529600000.

The previous prime is 21533999959. The next prime is 21534000043. The reversal of 21534000000 is 43512.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 221999952 + ... + 222000048.

Almost surely, 2^21534000000 is an apocalyptic number.

21534000000 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 21534000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37094056440).

21534000000 is an abundant number, since it is smaller than the sum of its proper divisors (52654112880).

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

21534000000 is an frugal number, since it uses more digits than its factorization.

21534000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181 (or 144 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

Adding to 21534000000 its reverse (43512), we get a palindrome (21534043512).

The spelling of 21534000000 in words is "twenty-one billion, five hundred thirty-four million", and thus it is an aban number.