1390644 has 18 divisors (see below), whose sum is σ = 3515330. Its totient is φ = 463536.

The previous prime is 1390643. The next prime is 1390681. The reversal of 1390644 is 4460931.

1390644 is a `hidden beast` number, since 13 + 9 + 0 + 644 = 666.

It can be written as a sum of positive squares in only one way, i.e., 810000 + 580644 = 900^2 + 762^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

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 5 ways as a sum of consecutive naturals, for example, 19279 + ... + 19350.

2^1390644 is an apocalyptic number.

It is an amenable number.

1390644 is an abundant number, since it is smaller than the sum of its proper divisors (2124686).

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

1390644 is a wasteful number, since it uses less digits than its factorization.

1390644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38639 (or 38634 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 1390644 is about 1179.2556974634. The cubic root of 1390644 is about 111.6191357328.

The spelling of 1390644 in words is "one million, three hundred ninety thousand, six hundred forty-four".