621557 has 4 divisors (see below), whose sum is σ = 643020. Its totient is φ = 600096.

The previous prime is 621541. The next prime is 621583. The reversal of 621557 is 755126.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 755126 = 2 ⋅377563.

It can be written as a sum of positive squares in 2 ways, for example, as 167281 + 454276 = 409^2 + 674^2 .

It is a cyclic number.

It is not a de Polignac number, because 621557 - 2⁴ = 621541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 621557.

It is not an unprimeable number, because it can be changed into a prime (621527) 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, 10688 + ... + 10745.

It is an arithmetic number, because the mean of its divisors is an integer number (160755).

2⁶²¹⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

621557 is a deficient number, since it is larger than the sum of its proper divisors (21463).

621557 is a wasteful number, since it uses less digits than its factorization.

621557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21462.

The product of its digits is 2100, while the sum is 26.

The square root of 621557 is about 788.3888634424. The cubic root of 621557 is about 85.3415095654.

The spelling of 621557 in words is "six hundred twenty-one thousand, five hundred fifty-seven".