21180231 has 48 divisors (see below), whose sum is σ = 34564320. Its totient is φ = 12804480.

The previous prime is 21180227. The next prime is 21180239. The reversal of 21180231 is 13208112.

It is not a de Polignac number, because 21180231 - 2² = 21180227 is a prime.

It is a super-2 number, since 2×21180231² = 897204370426722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21180239) 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 47 ways as a sum of consecutive naturals, for example, 399601 + ... + 399653.

It is an arithmetic number, because the mean of its divisors is an integer number (720090).

Almost surely, 2^21180231 is an apocalyptic number.

21180231 is a deficient number, since it is larger than the sum of its proper divisors (13384089).

21180231 is a wasteful number, since it uses less digits than its factorization.

21180231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21180231 is about 4602.1984963711. The cubic root of 21180231 is about 276.6794460315.

Adding to 21180231 its reverse (13208112), we get a palindrome (34388343).

The spelling of 21180231 in words is "twenty-one million, one hundred eighty thousand, two hundred thirty-one".