21311502012 has 144 divisors (see below), whose sum is σ = 58132069632. Its totient is φ = 6566165760.

The previous prime is 21311501999. The next prime is 21311502077. The reversal of 21311502012 is 21020511312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3629503 + ... + 3635369.

It is an arithmetic number, because the mean of its divisors is an integer number (403694928).

Almost surely, 2^21311502012 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 21311502012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29066034816).

21311502012 is an abundant number, since it is smaller than the sum of its proper divisors (36820567620).

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

21311502012 is a wasteful number, since it uses less digits than its factorization.

21311502012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6048 (or 6043 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The spelling of 21311502012 in words is "twenty-one billion, three hundred eleven million, five hundred two thousand, twelve".