253521661 has 2 divisors, whose sum is σ = 253521662. Its totient is φ = 253521660.

The previous prime is 253521659. The next prime is 253521703. The reversal of 253521661 is 166125352.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 233325625 + 20196036 = 15275^2 + 4494^2 .

It is a cyclic number.

It is not a de Polignac number, because 253521661 - 2¹ = 253521659 is a prime.

Together with 253521659, 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 (253521641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 126760830 + 126760831.

It is an arithmetic number, because the mean of its divisors is an integer number (126760831).

Almost surely, 2^253521661 is an apocalyptic number.

It is an amenable number.

253521661 is a deficient number, since it is larger than the sum of its proper divisors (1).

253521661 is an equidigital number, since it uses as much as digits as its factorization.

253521661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10800, while the sum is 31.

The square root of 253521661 is about 15922.3635494232. The cubic root of 253521661 is about 632.9047530405.

The spelling of 253521661 in words is "two hundred fifty-three million, five hundred twenty-one thousand, six hundred sixty-one".