13021661 has 4 divisors (see below), whose sum is σ = 13044000. Its totient is φ = 12999324.

The previous prime is 13021633. The next prime is 13021663. The reversal of 13021661 is 16612031.

13021661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 13021661 - 2⁶ = 13021597 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 (13021663) 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, 10271 + ... + 11468.

It is an arithmetic number, because the mean of its divisors is an integer number (3261000).

Almost surely, 2^13021661 is an apocalyptic number.

It is an amenable number.

13021661 is a deficient number, since it is larger than the sum of its proper divisors (22339).

13021661 is an equidigital number, since it uses as much as digits as its factorization.

13021661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22338.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 13021661 is about 3608.5538654702. The cubic root of 13021661 is about 235.2639918452.

Adding to 13021661 its reverse (16612031), we get a palindrome (29633692).

The spelling of 13021661 in words is "thirteen million, twenty-one thousand, six hundred sixty-one".