621216121 has 2 divisors, whose sum is σ = 621216122. Its totient is φ = 621216120.

The previous prime is 621216109. The next prime is 621216139. The reversal of 621216121 is 121612126.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 508006521 + 113209600 = 22539^2 + 10640^2 .

It is a cyclic number.

It is not a de Polignac number, because 621216121 - 2¹³ = 621207929 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 621216092 and 621216101.

It is not a weakly prime, because it can be changed into another prime (621216181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310608060 + 310608061.

It is an arithmetic number, because the mean of its divisors is an integer number (310608061).

Almost surely, 2^621216121 is an apocalyptic number.

It is an amenable number.

621216121 is a deficient number, since it is larger than the sum of its proper divisors (1).

621216121 is an equidigital number, since it uses as much as digits as its factorization.

621216121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 22.

The square root of 621216121 is about 24924.2075300299. The cubic root of 621216121 is about 853.2590550004.

Adding to 621216121 its reverse (121612126), we get a palindrome (742828247).

The spelling of 621216121 in words is "six hundred twenty-one million, two hundred sixteen thousand, one hundred twenty-one".