21919155 has 16 divisors (see below), whose sum is σ = 35817984. Its totient is φ = 11441120.

The previous prime is 21919129. The next prime is 21919159. The reversal of 21919155 is 55191912.

It is a happy number.

It is not a de Polignac number, because 21919155 - 2⁵ = 21919123 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21919159) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14841 + ... + 16250.

It is an arithmetic number, because the mean of its divisors is an integer number (2238624).

Almost surely, 2^21919155 is an apocalyptic number.

21919155 is a deficient number, since it is larger than the sum of its proper divisors (13898829).

21919155 is a wasteful number, since it uses less digits than its factorization.

21919155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31146.

The product of its digits is 4050, while the sum is 33.

The square root of 21919155 is about 4681.7897218906. The cubic root of 21919155 is about 279.8602831857.

The spelling of 21919155 in words is "twenty-one million, nine hundred nineteen thousand, one hundred fifty-five".