21521212512 has 96 divisors (see below), whose sum is σ = 57398471424. Its totient is φ = 7059648000.

The previous prime is 21521212507. The next prime is 21521212523.

21521212512 is nontrivially palindromic in base 10.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1612587 + ... + 1625877.

It is an arithmetic number, because the mean of its divisors is an integer number (597900744).

Almost surely, 2^21521212512 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21521212512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28699235712).

21521212512 is an abundant number, since it is smaller than the sum of its proper divisors (35877258912).

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

21521212512 is a wasteful number, since it uses less digits than its factorization.

21521212512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13572 (or 13564 counting only the distinct ones).

The product of its digits is 800, while the sum is 24.

The spelling of 21521212512 in words is "twenty-one billion, five hundred twenty-one million, two hundred twelve thousand, five hundred twelve".