621146821 has 2 divisors, whose sum is σ = 621146822. Its totient is φ = 621146820.

The previous prime is 621146819. The next prime is 621146863. The reversal of 621146821 is 128641126.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 508998721 + 112148100 = 22561^2 + 10590^2 .

It is a cyclic number.

It is not a de Polignac number, because 621146821 - 2¹ = 621146819 is a prime.

Together with 621146819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (621146881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310573410 + 310573411.

It is an arithmetic number, because the mean of its divisors is an integer number (310573411).

Almost surely, 2^621146821 is an apocalyptic number.

It is an amenable number.

621146821 is a deficient number, since it is larger than the sum of its proper divisors (1).

621146821 is an equidigital number, since it uses as much as digits as its factorization.

621146821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 31.

The square root of 621146821 is about 24922.8172765440. The cubic root of 621146821 is about 853.2273252747.

Adding to 621146821 its reverse (128641126), we get a palindrome (749787947).

The spelling of 621146821 in words is "six hundred twenty-one million, one hundred forty-six thousand, eight hundred twenty-one".