19809523840 has 64 divisors (see below), whose sum is σ = 47698056000. Its totient is φ = 7866768384.

The previous prime is 19809523831. The next prime is 19809523847. The reversal of 19809523840 is 4832590891.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (19809523847) 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, 22380 + ... + 200299.

It is an arithmetic number, because the mean of its divisors is an integer number (745282125).

Almost surely, 2^19809523840 is an apocalyptic number.

19809523840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19809523840 is an abundant number, since it is smaller than the sum of its proper divisors (27888532160).

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

19809523840 is a wasteful number, since it uses less digits than its factorization.

19809523840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222837 (or 222825 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 49.

The spelling of 19809523840 in words is "nineteen billion, eight hundred nine million, five hundred twenty-three thousand, eight hundred forty".