1642640 has 20 divisors (see below), whose sum is σ = 3819324. Its totient is φ = 657024.

The previous prime is 1642633. The next prime is 1642649. The reversal of 1642640 is 462461.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 861184 + 781456 = 928^2 + 884^2 .

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

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (1642649) 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, 10187 + ... + 10346.

2^1642640 is an apocalyptic number.

1642640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1642640 is an abundant number, since it is smaller than the sum of its proper divisors (2176684).

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

1642640 is a wasteful number, since it uses less digits than its factorization.

1642640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20546 (or 20540 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 1642640 is about 1281.6551798358. The cubic root of 1642640 is about 117.9906149770.

The spelling of 1642640 in words is "one million, six hundred forty-two thousand, six hundred forty".