21021231204 has 72 divisors (see below), whose sum is σ = 56351262240. Its totient is φ = 6584516352.

The previous prime is 21021231197. The next prime is 21021231269. The reversal of 21021231204 is 40213212012.

It is a happy number.

21021231204 is a `hidden beast` number, since 210 + 21 + 231 + 204 = 666.

It is a super-2 number, since 2×21021231204² (a number of 21 digits) contains 22 as substring.

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

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, 366807 + ... + 420225.

It is an arithmetic number, because the mean of its divisors is an integer number (782656420).

Almost surely, 2^21021231204 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 21021231204, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28175631120).

21021231204 is an abundant number, since it is smaller than the sum of its proper divisors (35330031036).

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

21021231204 is a wasteful number, since it uses less digits than its factorization.

21021231204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54089 (or 54084 counting only the distinct ones).

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

Adding to 21021231204 its reverse (40213212012), we get a palindrome (61234443216).

The spelling of 21021231204 in words is "twenty-one billion, twenty-one million, two hundred thirty-one thousand, two hundred four".