621355421 has 4 divisors (see below), whose sum is σ = 642781500. Its totient is φ = 599929344.

The previous prime is 621355409. The next prime is 621355429. The reversal of 621355421 is 124553126.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 124553126 = 2 ⋅62276563.

It can be written as a sum of positive squares in 2 ways, for example, as 305760196 + 315595225 = 17486^2 + 17765^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-621355421 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 21426049 = 621355421 / (6 + 2 + 1 + 3 + 5 + 5 + 4 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621355429) 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, 10712996 + ... + 10713053.

It is an arithmetic number, because the mean of its divisors is an integer number (160695375).

Almost surely, 2^621355421 is an apocalyptic number.

It is an amenable number.

621355421 is a deficient number, since it is larger than the sum of its proper divisors (21426079).

621355421 is a wasteful number, since it uses less digits than its factorization.

621355421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21426078.

The product of its digits is 7200, while the sum is 29.

The square root of 621355421 is about 24927.0018453885. The cubic root of 621355421 is about 853.3228278160.

The spelling of 621355421 in words is "six hundred twenty-one million, three hundred fifty-five thousand, four hundred twenty-one".