21155252 has 12 divisors (see below), whose sum is σ = 37490880. Its totient is φ = 10443576.

The previous prime is 21155219. The next prime is 21155257. The reversal of 21155252 is 25255112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33158 + ... + 33789.

It is an arithmetic number, because the mean of its divisors is an integer number (3124240).

Almost surely, 2^21155252 is an apocalyptic number.

It is an amenable number.

21155252 is a deficient number, since it is larger than the sum of its proper divisors (16335628).

21155252 is a wasteful number, since it uses less digits than its factorization.

21155252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67030 (or 67028 counting only the distinct ones).

The product of its digits is 1000, while the sum is 23.

The square root of 21155252 is about 4599.4838840896. The cubic root of 21155252 is about 276.5706355316.

The spelling of 21155252 in words is "twenty-one million, one hundred fifty-five thousand, two hundred fifty-two".