1355809621 has 4 divisors (see below), whose sum is σ = 1357812972. Its totient is φ = 1353806272.

The previous prime is 1355809603. The next prime is 1355809627. The reversal of 1355809621 is 1269085531.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 966339396 + 389470225 = 31086^2 + 19735^2 .

It is a cyclic number.

It is not a de Polignac number, because 1355809621 - 2²⁹ = 818938709 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1355809627) 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 in 3 ways as a sum of consecutive naturals, for example, 1000660 + ... + 1002013.

It is an arithmetic number, because the mean of its divisors is an integer number (339453243).

Almost surely, 2^1355809621 is an apocalyptic number.

It is an amenable number.

1355809621 is a deficient number, since it is larger than the sum of its proper divisors (2003351).

1355809621 is an equidigital number, since it uses as much as digits as its factorization.

1355809621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2003350.

The product of its (nonzero) digits is 64800, while the sum is 40.

The square root of 1355809621 is about 36821.3201963210. The cubic root of 1355809621 is about 1106.7925753807.

The spelling of 1355809621 in words is "one billion, three hundred fifty-five million, eight hundred nine thousand, six hundred twenty-one".