21772116 has 18 divisors (see below), whose sum is σ = 55035162. Its totient is φ = 7257360.

The previous prime is 21772111. The next prime is 21772123. The reversal of 21772116 is 61127712.

It can be written as a sum of positive squares in only one way, i.e., 21344400 + 427716 = 4620^2 + 654^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a self number, because there is not a number n which added to its sum of digits gives 21772116.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21772111) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 302355 + ... + 302426.

It is an arithmetic number, because the mean of its divisors is an integer number (3057509).

Almost surely, 2^21772116 is an apocalyptic number.

It is an amenable number.

21772116 is an abundant number, since it is smaller than the sum of its proper divisors (33263046).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21772116 is a wasteful number, since it uses less digits than its factorization.

21772116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604791 (or 604786 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 21772116 is about 4666.0600081868. The cubic root of 21772116 is about 279.2330884450.

Adding to 21772116 its reverse (61127712), we get a palindrome (82899828).

The spelling of 21772116 in words is "twenty-one million, seven hundred seventy-two thousand, one hundred sixteen".