19191920 has 80 divisors (see below), whose sum is σ = 49362912. Its totient is φ = 6881280.

The previous prime is 19191917. The next prime is 19191923. The reversal of 19191920 is 2919191.

It is an interprime number because it is at equal distance from previous prime (19191917) and next prime (19191923).

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19191923) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99344 + ... + 99536.

Almost surely, 2^19191920 is an apocalyptic number.

19191920 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 19191920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24681456).

19191920 is an abundant number, since it is smaller than the sum of its proper divisors (30170992).

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

19191920 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (19191919) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (330).

19191920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330 (or 324 counting only the distinct ones).

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

The square root of 19191920 is about 4380.8583633804. The cubic root of 19191920 is about 267.7356121358.

The spelling of 19191920 in words is "nineteen million, one hundred ninety-one thousand, nine hundred twenty".