10661209 has 4 divisors (see below), whose sum is σ = 11481316. Its totient is φ = 9841104.

The previous prime is 10661207. The next prime is 10661219. The reversal of 10661209 is 90216601.

10661209 is digitally balanced in base 2, 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.

It can be written as a sum of positive squares in 2 ways, for example, as 6051600 + 4609609 = 2460^2 + 2147^2 .

It is not a de Polignac number, because 10661209 - 2¹ = 10661207 is a prime.

It is a super-2 number, since 2×10661209² = 227322754683362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10661201) 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, 410034 + ... + 410059.

It is an arithmetic number, because the mean of its divisors is an integer number (2870329).

Almost surely, 2^10661209 is an apocalyptic number.

It is an amenable number.

10661209 is a deficient number, since it is larger than the sum of its proper divisors (820107).

10661209 is an equidigital number, since it uses as much as digits as its factorization.

10661209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820106.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 10661209 is about 3265.1506856499. The cubic root of 10661209 is about 220.0909334833.

The spelling of 10661209 in words is "ten million, six hundred sixty-one thousand, two hundred nine".