19921440 has 288 divisors, whose sum is σ = 80438400. Its totient is φ = 4139520.

The previous prime is 19921439. The next prime is 19921453. The reversal of 19921440 is 4412991.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 19921398 and 19921407.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1811035 + ... + 1811045.

It is an arithmetic number, because the mean of its divisors is an integer number (279300).

Almost surely, 2^19921440 is an apocalyptic number.

19921440 is a gapful number since it is divisible by the number (10) 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 19921440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40219200).

19921440 is an abundant number, since it is smaller than the sum of its proper divisors (60516960).

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

19921440 is a wasteful number, since it uses less digits than its factorization.

19921440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 19921440 is about 4463.3440378263. The cubic root of 19921440 is about 271.0858875475.

The spelling of 19921440 in words is "nineteen million, nine hundred twenty-one thousand, four hundred forty".