19910928640 has 36 divisors (see below), whose sum is σ = 47692899324. Its totient is φ = 7964370944.

The previous prime is 19910928619. The next prime is 19910928643. The reversal of 19910928640 is 4682901991.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 7064066304 + 12846862336 = 84048^2 + 113344^2 .

It is not an unprimeable number, because it can be changed into a prime (19910928643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7776427 + ... + 7778986.

It is an arithmetic number, because the mean of its divisors is an integer number (1324802759).

Almost surely, 2^19910928640 is an apocalyptic number.

19910928640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19910928640 is an abundant number, since it is smaller than the sum of its proper divisors (27781970684).

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

19910928640 is an equidigital number, since it uses as much as digits as its factorization.

19910928640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15555434 (or 15555420 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 49.

The spelling of 19910928640 in words is "nineteen billion, nine hundred ten million, nine hundred twenty-eight thousand, six hundred forty".