21123432320 has 32 divisors (see below), whose sum is σ = 50498206920. Its totient is φ = 8449372672.

The previous prime is 21123432307. The next prime is 21123432329. The reversal of 21123432320 is 2323432112.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123432329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16502042 + ... + 16503321.

Almost surely, 2^21123432320 is an apocalyptic number.

21123432320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21123432320 is an abundant number, since it is smaller than the sum of its proper divisors (29374774600).

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

21123432320 is an equidigital number, since it uses as much as digits as its factorization.

21123432320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33005382 (or 33005370 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

Adding to 21123432320 its reverse (2323432112), we get a palindrome (23446864432).

The spelling of 21123432320 in words is "twenty-one billion, one hundred twenty-three million, four hundred thirty-two thousand, three hundred twenty".