19561920 has 224 divisors, whose sum is σ = 73737216. Its totient is φ = 4300800.

The previous prime is 19561909. The next prime is 19561957. The reversal of 19561920 is 2916591.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 275485 + ... + 275555.

It is an arithmetic number, because the mean of its divisors is an integer number (329184).

Almost surely, 2^19561920 is an apocalyptic number.

19561920 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 19561920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36868608).

19561920 is an abundant number, since it is smaller than the sum of its proper divisors (54175296).

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

19561920 is a wasteful number, since it uses less digits than its factorization.

19561920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139 (or 129 counting only the distinct ones).

The product of its (nonzero) digits is 4860, while the sum is 33.

The square root of 19561920 is about 4422.8859356759. The cubic root of 19561920 is about 269.4452257587.

The spelling of 19561920 in words is "nineteen million, five hundred sixty-one thousand, nine hundred twenty".