21252231 has 72 divisors (see below), whose sum is σ = 42076944. Its totient is φ = 10160640.

The previous prime is 21252223. The next prime is 21252239. The reversal of 21252231 is 13225212.

It is an interprime number because it is at equal distance from previous prime (21252223) and next prime (21252239).

It is not a de Polignac number, because 21252231 - 2³ = 21252223 is a prime.

It is a super-2 number, since 2×21252231² = 903314644954722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252239) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 62895 + ... + 63231.

It is an arithmetic number, because the mean of its divisors is an integer number (584402).

Almost surely, 2^21252231 is an apocalyptic number.

21252231 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21252231 is a deficient number, since it is larger than the sum of its proper divisors (20824713).

21252231 is a wasteful number, since it uses less digits than its factorization.

21252231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 381 (or 371 counting only the distinct ones).

The product of its digits is 240, while the sum is 18.

The square root of 21252231 is about 4610.0142082211. The cubic root of 21252231 is about 276.9926058143.

Adding to 21252231 its reverse (13225212), we get a palindrome (34477443).

It can be divided in two parts, 2125 and 2231, that added together give a square (4356 = 66²).

The spelling of 21252231 in words is "twenty-one million, two hundred fifty-two thousand, two hundred thirty-one".