19907840 has 72 divisors (see below), whose sum is σ = 48467328. Its totient is φ = 7833600.

The previous prime is 19907831. The next prime is 19907851. The reversal of 19907840 is 4870991.

It is a junction number, because it is equal to n+sod(n) for n = 19907794 and 19907803.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131765 + ... + 131915.

Almost surely, 2^19907840 is an apocalyptic number.

19907840 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 19907840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24233664).

19907840 is an abundant number, since it is smaller than the sum of its proper divisors (28559488).

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

19907840 is a wasteful number, since it uses less digits than its factorization.

19907840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275 (or 261 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 19907840 is about 4461.8202563528. The cubic root of 19907840 is about 271.0241850576.

The spelling of 19907840 in words is "nineteen million, nine hundred seven thousand, eight hundred forty".