621743021 has 4 divisors (see below), whose sum is σ = 622090044. Its totient is φ = 621396000.

The previous prime is 621742999. The next prime is 621743029. The reversal of 621743021 is 120347126.

621743021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120347126 = 2 ⋅60173563.

It can be written as a sum of positive squares in 2 ways, for example, as 119355625 + 502387396 = 10925^2 + 22414^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-621743021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621743029) 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, 170810 + ... + 174411.

It is an arithmetic number, because the mean of its divisors is an integer number (155522511).

Almost surely, 2^621743021 is an apocalyptic number.

It is an amenable number.

621743021 is a deficient number, since it is larger than the sum of its proper divisors (347023).

621743021 is a wasteful number, since it uses less digits than its factorization.

621743021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347022.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 621743021 is about 24934.7753348612. The cubic root of 621743021 is about 853.5002245025.

The spelling of 621743021 in words is "six hundred twenty-one million, seven hundred forty-three thousand, twenty-one".