621840 has 40 divisors (see below), whose sum is σ = 1928448. Its totient is φ = 165760.

The previous prime is 621833. The next prime is 621869. The reversal of 621840 is 48126.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1056 + ... + 1535.

2⁶²¹⁸⁴⁰ is an apocalyptic number.

621840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

621840 is an abundant number, since it is smaller than the sum of its proper divisors (1306608).

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

621840 is a wasteful number, since it uses less digits than its factorization.

621840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2607 (or 2601 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 621840 is about 788.5683229753. The cubic root of 621840 is about 85.3544598299.

Adding to 621840 its reverse (48126), we get a palindrome (669966).

The spelling of 621840 in words is "six hundred twenty-one thousand, eight hundred forty".