21752231 has 8 divisors (see below), whose sum is σ = 23073840. Its totient is φ = 20435328.

The previous prime is 21752221. The next prime is 21752239. The reversal of 21752231 is 13225712.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21752231 - 2¹⁰ = 21751207 is a prime.

It is a super-2 number, since 2×21752231² = 946319106954722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21752197 and 21752206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21752239) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14180 + ... + 15638.

It is an arithmetic number, because the mean of its divisors is an integer number (2884230).

Almost surely, 2^21752231 is an apocalyptic number.

21752231 is a deficient number, since it is larger than the sum of its proper divisors (1321609).

21752231 is a wasteful number, since it uses less digits than its factorization.

21752231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2353.

The product of its digits is 840, while the sum is 23.

The square root of 21752231 is about 4663.9287087176. The cubic root of 21752231 is about 279.1480524407.

Adding to 21752231 its reverse (13225712), we get a palindrome (34977943).

The spelling of 21752231 in words is "twenty-one million, seven hundred fifty-two thousand, two hundred thirty-one".