21194169920 has 336 divisors, whose sum is σ = 64721524608. Its totient is φ = 6536355840.

The previous prime is 21194169877. The next prime is 21194169929. The reversal of 21194169920 is 2996149112.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is not an unprimeable number, because it can be changed into a prime (21194169929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 17764844 + ... + 17766036.

Almost surely, 2^21194169920 is an apocalyptic number.

21194169920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21194169920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32360762304).

21194169920 is an abundant number, since it is smaller than the sum of its proper divisors (43527354688).

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

21194169920 is a wasteful number, since it uses less digits than its factorization.

21194169920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1338 (or 1321 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 44.

The spelling of 21194169920 in words is "twenty-one billion, one hundred ninety-four million, one hundred sixty-nine thousand, nine hundred twenty".