621861 has 4 divisors (see below), whose sum is σ = 829152. Its totient is φ = 414572.

The previous prime is 621833. The next prime is 621869. The reversal of 621861 is 168126.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 621861 - 2¹¹ = 619813 is a prime.

It is a super-2 number, since 2×621861² = 773422206642, which contains 22 as substring.

It is a D-number.

621861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621869) by changing a digit.

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, 103641 + ... + 103646.

It is an arithmetic number, because the mean of its divisors is an integer number (207288).

2⁶²¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

621861 is a deficient number, since it is larger than the sum of its proper divisors (207291).

621861 is a wasteful number, since it uses less digits than its factorization.

621861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207290.

The product of its digits is 576, while the sum is 24.

The square root of 621861 is about 788.5816381327. The cubic root of 621861 is about 85.3554206470.

Adding to 621861 its reverse (168126), we get a palindrome (789987).

The spelling of 621861 in words is "six hundred twenty-one thousand, eight hundred sixty-one".