21998748420 has 384 divisors, whose sum is σ = 76720089600. Its totient is φ = 5188147200.

The previous prime is 21998748407. The next prime is 21998748503. The reversal of 21998748420 is 2484789912.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 39494782 + ... + 39495338.

It is an arithmetic number, because the mean of its divisors is an integer number (199791900).

Almost surely, 2^21998748420 is an apocalyptic number.

21998748420 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 21998748420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38360044800).

21998748420 is an abundant number, since it is smaller than the sum of its proper divisors (54721341180).

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

21998748420 is a wasteful number, since it uses less digits than its factorization.

21998748420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 54.

The spelling of 21998748420 in words is "twenty-one billion, nine hundred ninety-eight million, seven hundred forty-eight thousand, four hundred twenty".