621563561 has 2 divisors, whose sum is σ = 621563562. Its totient is φ = 621563560.

The previous prime is 621563557. The next prime is 621563573. The reversal of 621563561 is 165365126.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 346667161 + 274896400 = 18619^2 + 16580^2 .

It is a cyclic number.

It is not a de Polignac number, because 621563561 - 2² = 621563557 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (621565561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310781780 + 310781781.

It is an arithmetic number, because the mean of its divisors is an integer number (310781781).

Almost surely, 2^621563561 is an apocalyptic number.

It is an amenable number.

621563561 is a deficient number, since it is larger than the sum of its proper divisors (1).

621563561 is an equidigital number, since it uses as much as digits as its factorization.

621563561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 35.

The square root of 621563561 is about 24931.1764864797. The cubic root of 621563561 is about 853.4180984556.

It can be divided in two parts, 621563 and 561, that multiplied together give a palindrome (348696843).

The spelling of 621563561 in words is "six hundred twenty-one million, five hundred sixty-three thousand, five hundred sixty-one".