621565121 has 2 divisors, whose sum is σ = 621565122. Its totient is φ = 621565120.

The previous prime is 621565111. The next prime is 621565123. The reversal of 621565121 is 121565126.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 339996721 + 281568400 = 18439^2 + 16780^2 .

It is a cyclic number.

It is not a de Polignac number, because 621565121 - 2⁶ = 621565057 is a prime.

Together with 621565123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (621565123) 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 as a sum of consecutive naturals, namely, 310782560 + 310782561.

It is an arithmetic number, because the mean of its divisors is an integer number (310782561).

Almost surely, 2^621565121 is an apocalyptic number.

It is an amenable number.

621565121 is a deficient number, since it is larger than the sum of its proper divisors (1).

621565121 is an equidigital number, since it uses as much as digits as its factorization.

621565121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 29.

The square root of 621565121 is about 24931.2077725890. The cubic root of 621565121 is about 853.4188124245.

The spelling of 621565121 in words is "six hundred twenty-one million, five hundred sixty-five thousand, one hundred twenty-one".