21961155 has 16 divisors (see below), whose sum is σ = 35239680. Its totient is φ = 11678688.

The previous prime is 21961151. The next prime is 21961171. The reversal of 21961155 is 55116912.

It is not a de Polignac number, because 21961155 - 2² = 21961151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21961151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3754 + ... + 7616.

It is an arithmetic number, because the mean of its divisors is an integer number (2202480).

Almost surely, 2^21961155 is an apocalyptic number.

21961155 is a deficient number, since it is larger than the sum of its proper divisors (13278525).

21961155 is a wasteful number, since it uses less digits than its factorization.

21961155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4250.

The product of its digits is 2700, while the sum is 30.

The square root of 21961155 is about 4686.2730394206. The cubic root of 21961155 is about 280.0389189099.

The spelling of 21961155 in words is "twenty-one million, nine hundred sixty-one thousand, one hundred fifty-five".