21323121012 has 72 divisors (see below), whose sum is σ = 57126730752. Its totient is φ = 6683040000.

The previous prime is 21323121011. The next prime is 21323121023. The reversal of 21323121012 is 21012132312.

21323121012 is a `hidden beast` number, since 213 + 231 + 210 + 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 not an unprimeable number, because it can be changed into a prime (21323121011) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 626637 + ... + 659787.

It is an arithmetic number, because the mean of its divisors is an integer number (793426816).

Almost surely, 2^21323121012 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 21323121012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28563365376).

21323121012 is an abundant number, since it is smaller than the sum of its proper divisors (35803609740).

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

21323121012 is a wasteful number, since it uses less digits than its factorization.

21323121012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34229 (or 34224 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21323121012 its reverse (21012132312), we get a palindrome (42335253324).

The spelling of 21323121012 in words is "twenty-one billion, three hundred twenty-three million, one hundred twenty-one thousand, twelve".