1398640 has 20 divisors (see below), whose sum is σ = 3252024. Its totient is φ = 559424.

The previous prime is 1398623. The next prime is 1398659. The reversal of 1398640 is 468931.

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

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

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, 8662 + ... + 8821.

2^1398640 is an apocalyptic number.

1398640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1398640 is an abundant number, since it is smaller than the sum of its proper divisors (1853384).

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

1398640 is a wasteful number, since it uses less digits than its factorization.

1398640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17496 (or 17490 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 1398640 is about 1182.6411120877. The cubic root of 1398640 is about 111.8326582587.

The spelling of 1398640 in words is "one million, three hundred ninety-eight thousand, six hundred forty".