21231402012 has 72 divisors (see below), whose sum is σ = 55195904400. Its totient is φ = 6876223488.

The previous prime is 21231402007. The next prime is 21231402037. The reversal of 21231402012 is 21020413212.

It is a happy number.

21231402012 is a `hidden beast` number, since 21 + 231 + 402 + 0 + 12 = 666.

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 23 ways as a sum of consecutive naturals, for example, 973564 + ... + 995132.

Almost surely, 2^21231402012 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 21231402012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27597952200).

21231402012 is an abundant number, since it is smaller than the sum of its proper divisors (33964502388).

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

21231402012 is a wasteful number, since it uses less digits than its factorization.

21231402012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22355 (or 22350 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21231402012 its reverse (21020413212), we get a palindrome (42251815224).

The spelling of 21231402012 in words is "twenty-one billion, two hundred thirty-one million, four hundred two thousand, twelve".