1290165521 has 4 divisors (see below), whose sum is σ = 1298824500. Its totient is φ = 1281506544.

The previous prime is 1290165497. The next prime is 1290165523. The reversal of 1290165521 is 1255610921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1255610921 = 937 ⋅1340033.

It can be written as a sum of positive squares in 2 ways, for example, as 693584896 + 596580625 = 26336^2 + 24425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1290165521 - 2¹⁰ = 1290164497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1290165523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4329266 + ... + 4329563.

It is an arithmetic number, because the mean of its divisors is an integer number (324706125).

Almost surely, 2^1290165521 is an apocalyptic number.

It is an amenable number.

1290165521 is a deficient number, since it is larger than the sum of its proper divisors (8658979).

1290165521 is an equidigital number, since it uses as much as digits as its factorization.

1290165521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8658978.

The product of its (nonzero) digits is 5400, while the sum is 32.

The square root of 1290165521 is about 35918.8741610870. The cubic root of 1290165521 is about 1088.6337906471.

The spelling of 1290165521 in words is "one billion, two hundred ninety million, one hundred sixty-five thousand, five hundred twenty-one".