19961720 has 32 divisors (see below), whose sum is σ = 45489600. Its totient is φ = 7882368.

The previous prime is 19961719. The next prime is 19961729. The reversal of 19961720 is 2716991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19961729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2 + ... + 6318.

It is an arithmetic number, because the mean of its divisors is an integer number (1421550).

Almost surely, 2^19961720 is an apocalyptic number.

19961720 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 19961720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22744800).

19961720 is an abundant number, since it is smaller than the sum of its proper divisors (25527880).

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

19961720 is a wasteful number, since it uses less digits than its factorization.

19961720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6407 (or 6403 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 19961720 is about 4467.8540710278. The cubic root of 19961720 is about 271.2684712092.

The spelling of 19961720 in words is "nineteen million, nine hundred sixty-one thousand, seven hundred twenty".