11166721 has 6 divisors (see below), whose sum is σ = 11356566. Its totient is φ = 10980000.

The previous prime is 11166703. The next prime is 11166731. The reversal of 11166721 is 12766111.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 408321 + 10758400 = 639^2 + 3280^2 .

It is a de Polignac number, because none of the positive numbers 2^k-11166721 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 (11166731) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2221 + ... + 5221.

It is an arithmetic number, because the mean of its divisors is an integer number (1892761).

Almost surely, 2^11166721 is an apocalyptic number.

It is an amenable number.

11166721 is a deficient number, since it is larger than the sum of its proper divisors (189845).

11166721 is an frugal number, since it uses more digits than its factorization.

11166721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3123 (or 3062 counting only the distinct ones).

The product of its digits is 504, while the sum is 25.

The square root of 11166721 is about 3341.6644056518. The cubic root of 11166721 is about 223.5159682766.

The spelling of 11166721 in words is "eleven million, one hundred sixty-six thousand, seven hundred twenty-one".