21214155 has 16 divisors (see below), whose sum is σ = 34665984. Its totient is φ = 11073120.

The previous prime is 21214139. The next prime is 21214159. The reversal of 21214155 is 55141212.

It is not a de Polignac number, because 21214155 - 2⁴ = 21214139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21214159) 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, 14341 + ... + 15750.

It is an arithmetic number, because the mean of its divisors is an integer number (2166624).

Almost surely, 2^21214155 is an apocalyptic number.

21214155 is a deficient number, since it is larger than the sum of its proper divisors (13451829).

21214155 is a wasteful number, since it uses less digits than its factorization.

21214155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30146.

The product of its digits is 400, while the sum is 21.

The square root of 21214155 is about 4605.8826515664. The cubic root of 21214155 is about 276.8270847552.

Adding to 21214155 its reverse (55141212), we get a palindrome (76355367).

The spelling of 21214155 in words is "twenty-one million, two hundred fourteen thousand, one hundred fifty-five".