13201021661 has 4 divisors (see below), whose sum is σ = 13205254524. Its totient is φ = 13196788800.

The previous prime is 13201021633. The next prime is 13201021663. The reversal of 13201021661 is 16612010231.

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 94206436 + 13106815225 = 9706^2 + 114485^2 .

It is a cyclic number.

It is not a de Polignac number, because 13201021661 - 2⁶ = 13201021597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13201021663) 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, 2111750 + ... + 2117991.

It is an arithmetic number, because the mean of its divisors is an integer number (3301313631).

Almost surely, 2^13201021661 is an apocalyptic number.

It is an amenable number.

13201021661 is a deficient number, since it is larger than the sum of its proper divisors (4232863).

13201021661 is an equidigital number, since it uses as much as digits as its factorization.

13201021661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4232862.

The product of its (nonzero) digits is 432, while the sum is 23.

Adding to 13201021661 its reverse (16612010231), we get a palindrome (29813031892).

The spelling of 13201021661 in words is "thirteen billion, two hundred one million, twenty-one thousand, six hundred sixty-one".