21312123020 has 48 divisors (see below), whose sum is σ = 44931474336. Its totient is φ = 8491392000.

The previous prime is 21312122971. The next prime is 21312123029. The reversal of 21312123020 is 2032121312.

It is a super-2 number, since 2×21312123020² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21312123020.

It is not an unprimeable number, because it can be changed into a prime (21312123029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6827060 + ... + 6830180.

It is an arithmetic number, because the mean of its divisors is an integer number (936072382).

Almost surely, 2^21312123020 is an apocalyptic number.

21312123020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21312123020 is an abundant number, since it is smaller than the sum of its proper divisors (23619351316).

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

21312123020 is a wasteful number, since it uses less digits than its factorization.

21312123020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4362 (or 4360 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21312123020 its reverse (2032121312), we get a palindrome (23344244332).

The spelling of 21312123020 in words is "twenty-one billion, three hundred twelve million, one hundred twenty-three thousand, twenty".