1021640 has 16 divisors (see below), whose sum is σ = 2298780. Its totient is φ = 408640.

The previous prime is 1021627. The next prime is 1021651. The reversal of 1021640 is 461201.

It can be written as a sum of positive squares in 2 ways, for example, as 1012036 + 9604 = 1006^2 + 98^2 .

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, 12731 + ... + 12810.

2^1021640 is an apocalyptic number.

1021640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1021640 is an abundant number, since it is smaller than the sum of its proper divisors (1277140).

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

1021640 is a wasteful number, since it uses less digits than its factorization.

1021640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25552 (or 25548 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 1021640 is about 1010.7620887232. The cubic root of 1021640 is about 100.7161917814.

Adding to 1021640 its reverse (461201), we get a palindrome (1482841).

It can be divided in two parts, 1021 and 640, that added together give a palindrome (1661).

The spelling of 1021640 in words is "one million, twenty-one thousand, six hundred forty".