19891521440 has 96 divisors (see below), whose sum is σ = 53752616064. Its totient is φ = 6814172160.

The previous prime is 19891521437. The next prime is 19891521451. The reversal of 19891521440 is 4412519891.

It is a junction number, because it is equal to n+sod(n) for n = 19891521391 and 19891521400.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1439042 + ... + 1452798.

It is an arithmetic number, because the mean of its divisors is an integer number (559923084).

Almost surely, 2^19891521440 is an apocalyptic number.

19891521440 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 19891521440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26876308032).

19891521440 is an abundant number, since it is smaller than the sum of its proper divisors (33861094624).

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

19891521440 is a wasteful number, since it uses less digits than its factorization.

19891521440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15070 (or 15062 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 44.

The spelling of 19891521440 in words is "nineteen billion, eight hundred ninety-one million, five hundred twenty-one thousand, four hundred forty".