21011344536 has 128 divisors (see below), whose sum is σ = 64909555200. Its totient is φ = 5519232000.

The previous prime is 21011344499. The next prime is 21011344559. The reversal of 21011344536 is 63544311012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 529020 + ... + 567348.

It is an arithmetic number, because the mean of its divisors is an integer number (507105900).

Almost surely, 2^21011344536 is an apocalyptic number.

21011344536 is a gapful number since it is divisible by the number (26) 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 21011344536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32454777600).

21011344536 is an abundant number, since it is smaller than the sum of its proper divisors (43898210664).

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

21011344536 is a wasteful number, since it uses less digits than its factorization.

21011344536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38609 (or 38605 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

Adding to 21011344536 its reverse (63544311012), we get a palindrome (84555655548).

The spelling of 21011344536 in words is "twenty-one billion, eleven million, three hundred forty-four thousand, five hundred thirty-six".