21772213 has 4 divisors (see below), whose sum is σ = 21786208. Its totient is φ = 21758220.

The previous prime is 21772211. The next prime is 21772229. The reversal of 21772213 is 31227712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21772213 - 2¹ = 21772211 is a prime.

It is a Duffinian number.

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, 4323 + ... + 7888.

It is an arithmetic number, because the mean of its divisors is an integer number (5446552).

Almost surely, 2^21772213 is an apocalyptic number.

It is an amenable number.

21772213 is a deficient number, since it is larger than the sum of its proper divisors (13995).

21772213 is a wasteful number, since it uses less digits than its factorization.

21772213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13994.

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

The square root of 21772213 is about 4666.0704023836. The cubic root of 21772213 is about 279.2335031278.

Adding to 21772213 its reverse (31227712), we get a palindrome (52999925).

The spelling of 21772213 in words is "twenty-one million, seven hundred seventy-two thousand, two hundred thirteen".