21002121232 has 80 divisors (see below), whose sum is σ = 44746903872. Its totient is φ = 9509068800.

The previous prime is 21002121223. The next prime is 21002121247. The reversal of 21002121232 is 23212120012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (16).

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, 770232 + ... + 797032.

Almost surely, 2^21002121232 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 21002121232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22373451936).

21002121232 is an abundant number, since it is smaller than the sum of its proper divisors (23744782640).

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

21002121232 is a wasteful number, since it uses less digits than its factorization.

21002121232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26936 (or 26930 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21002121232 its reverse (23212120012), we get a palindrome (44214241244).

The spelling of 21002121232 in words is "twenty-one billion, two million, one hundred twenty-one thousand, two hundred thirty-two".