1390640 has 20 divisors (see below), whose sum is σ = 3233424. Its totient is φ = 556224.

The previous prime is 1390639. The next prime is 1390643. The reversal of 1390640 is 460931.

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

It is not an unprimeable number, because it can be changed into a prime (1390643) 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, 8612 + ... + 8771.

2^1390640 is an apocalyptic number.

1390640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1390640 is an abundant number, since it is smaller than the sum of its proper divisors (1842784).

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

1390640 is a wasteful number, since it uses less digits than its factorization.

1390640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17396 (or 17390 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 1390640 is about 1179.2540014772. The cubic root of 1390640 is about 111.6190287136.

The spelling of 1390640 in words is "one million, three hundred ninety thousand, six hundred forty".