11155721 has 2 divisors, whose sum is σ = 11155722. Its totient is φ = 11155720.

The previous prime is 11155673. The next prime is 11155747. The reversal of 11155721 is 12755111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11155600 + 121 = 3340^2 + 11^2 .

It is a cyclic number.

It is not a de Polignac number, because 11155721 - 2⁶ = 11155657 is a prime.

It is a super-2 number, since 2×11155721² = 248900222059682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (11155751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5577860 + 5577861.

It is an arithmetic number, because the mean of its divisors is an integer number (5577861).

Almost surely, 2^11155721 is an apocalyptic number.

It is an amenable number.

11155721 is a deficient number, since it is larger than the sum of its proper divisors (1).

11155721 is an equidigital number, since it uses as much as digits as its factorization.

11155721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 350, while the sum is 23.

The square root of 11155721 is about 3340.0181137233. The cubic root of 11155721 is about 223.4425512184.

The spelling of 11155721 in words is "eleven million, one hundred fifty-five thousand, seven hundred twenty-one".