1399637840 has 20 divisors (see below), whose sum is σ = 3254158164. Its totient is φ = 559855104.

The previous prime is 1399637821. The next prime is 1399637849. The reversal of 1399637840 is 487369931.

It can be written as a sum of positive squares in 2 ways, for example, as 148742416 + 1250895424 = 12196^2 + 35368^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1399637849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8747657 + ... + 8747816.

Almost surely, 2^1399637840 is an apocalyptic number.

1399637840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1399637840 is an abundant number, since it is smaller than the sum of its proper divisors (1854520324).

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

1399637840 is a wasteful number, since it uses less digits than its factorization.

1399637840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17495486 (or 17495480 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 50.

The square root of 1399637840 is about 37411.7339881487. The cubic root of 1399637840 is about 1118.5924708130.

The spelling of 1399637840 in words is "one billion, three hundred ninety-nine million, six hundred thirty-seven thousand, eight hundred forty".