19791440 has 20 divisors (see below), whose sum is σ = 46015284. Its totient is φ = 7916544.

The previous prime is 19791439. The next prime is 19791461. The reversal of 19791440 is 4419791.

It can be written as a sum of positive squares in 2 ways, for example, as 13278736 + 6512704 = 3644^2 + 2552^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 19791440.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123617 + ... + 123776.

Almost surely, 2^19791440 is an apocalyptic number.

19791440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19791440 is an abundant number, since it is smaller than the sum of its proper divisors (26223844).

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

19791440 is a wasteful number, since it uses less digits than its factorization.

19791440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247406 (or 247400 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 19791440 is about 4448.7571298060. The cubic root of 19791440 is about 270.4949312467.

The spelling of 19791440 in words is "nineteen million, seven hundred ninety-one thousand, four hundred forty".