21998719440 has 120 divisors (see below), whose sum is σ = 78224901768. Its totient is φ = 5521244160.

The previous prime is 21998719439. The next prime is 21998719451. The reversal of 21998719440 is 4491789912.

21998719440 is a `hidden beast` number, since 2 + 199 + 8 + 7 + 1 + 9 + 440 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 12013913664 + 9984805776 = 109608^2 + 99924^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 886401 + ... + 910880.

Almost surely, 2^21998719440 is an apocalyptic number.

21998719440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21998719440 is an abundant number, since it is smaller than the sum of its proper divisors (56226182328).

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

21998719440 is a wasteful number, since it uses less digits than its factorization.

21998719440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1797317 (or 1797308 counting only the distinct ones).

The product of its (nonzero) digits is 1306368, while the sum is 54.

The spelling of 21998719440 in words is "twenty-one billion, nine hundred ninety-eight million, seven hundred nineteen thousand, four hundred forty".