19911920 has 120 divisors (see below), whose sum is σ = 56148192. Its totient is φ = 6428160.

The previous prime is 19911919. The next prime is 19911923. The reversal of 19911920 is 2911991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19911923) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 538142 + ... + 538178.

Almost surely, 2^19911920 is an apocalyptic number.

19911920 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 19911920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28074096).

19911920 is an abundant number, since it is smaller than the sum of its proper divisors (36236272).

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

19911920 is a wasteful number, since it uses less digits than its factorization.

19911920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 19911920 is about 4462.2774454308. The cubic root of 19911920 is about 271.0426987544.

The spelling of 19911920 in words is "nineteen million, nine hundred eleven thousand, nine hundred twenty".