621521 has 2 divisors, whose sum is σ = 621522. Its totient is φ = 621520.

The previous prime is 621473. The next prime is 621527. The reversal of 621521 is 125126.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 440896 + 180625 = 664^2 + 425^2 .

It is a cyclic number.

It is not a de Polignac number, because 621521 - 2¹⁸ = 359377 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 621521.

It is not a weakly prime, because it can be changed into another prime (621527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310760 + 310761.

It is an arithmetic number, because the mean of its divisors is an integer number (310761).

2⁶²¹⁵²¹ is an apocalyptic number.

It is an amenable number.

621521 is a deficient number, since it is larger than the sum of its proper divisors (1).

621521 is an equidigital number, since it uses as much as digits as its factorization.

621521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120, while the sum is 17.

The square root of 621521 is about 788.3660317391. The cubic root of 621521 is about 85.3398619001.

Adding to 621521 its reverse (125126), we get a palindrome (746647).

The spelling of 621521 in words is "six hundred twenty-one thousand, five hundred twenty-one".