621591 has 4 divisors (see below), whose sum is σ = 828792. Its totient is φ = 414392.

The previous prime is 621583. The next prime is 621611. The reversal of 621591 is 195126.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 621591 - 2³ = 621583 is a prime.

It is a D-number.

621591 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621521) 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, 103596 + ... + 103601.

It is an arithmetic number, because the mean of its divisors is an integer number (207198).

2⁶²¹⁵⁹¹ is an apocalyptic number.

621591 is a deficient number, since it is larger than the sum of its proper divisors (207201).

621591 is a wasteful number, since it uses less digits than its factorization.

621591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207200.

The product of its digits is 540, while the sum is 24.

The square root of 621591 is about 788.4104261107. The cubic root of 621591 is about 85.3430656353.

It can be divided in two parts, 6215 and 91, that multiplied together give a palindrome (565565).

The spelling of 621591 in words is "six hundred twenty-one thousand, five hundred ninety-one".