1645640 has 16 divisors (see below), whose sum is σ = 3702780. Its totient is φ = 658240.

The previous prime is 1645613. The next prime is 1645643. The reversal of 1645640 is 465461.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1643524 + 2116 = 1282^2 + 46^2 .

It is not an unprimeable number, because it can be changed into a prime (1645643) 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, 20531 + ... + 20610.

2^1645640 is an apocalyptic number.

1645640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1645640 is an abundant number, since it is smaller than the sum of its proper divisors (2057140).

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

1645640 is a wasteful number, since it uses less digits than its factorization.

1645640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41152 (or 41148 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 1645640 is about 1282.8250075517. The cubic root of 1645640 is about 118.0624011614.

The spelling of 1645640 in words is "one million, six hundred forty-five thousand, six hundred forty".