21772231 has 4 divisors (see below), whose sum is σ = 23447032. Its totient is φ = 20097432.

The previous prime is 21772229. The next prime is 21772259. The reversal of 21772231 is 13227712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21772231 - 2¹ = 21772229 is a prime.

It is a super-2 number, since 2×21772231² = 948060085434722, 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 = 21772196 and 21772205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21772211) 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, 837381 + ... + 837406.

It is an arithmetic number, because the mean of its divisors is an integer number (5861758).

Almost surely, 2^21772231 is an apocalyptic number.

21772231 is a deficient number, since it is larger than the sum of its proper divisors (1674801).

21772231 is a wasteful number, since it uses less digits than its factorization.

21772231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1674800.

The product of its digits is 1176, while the sum is 25.

The square root of 21772231 is about 4666.0723312010. The cubic root of 21772231 is about 279.2335800792.

Adding to 21772231 its reverse (13227712), we get a palindrome (34999943).

The spelling of 21772231 in words is "twenty-one million, seven hundred seventy-two thousand, two hundred thirty-one".