21928772 has 6 divisors (see below), whose sum is σ = 38375358. Its totient is φ = 10964384.

The previous prime is 21928769. The next prime is 21928787. The reversal of 21928772 is 27782912.

It can be written as a sum of positive squares in only one way, i.e., 19219456 + 2709316 = 4384^2 + 1646^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2741093 + ... + 2741100.

It is an arithmetic number, because the mean of its divisors is an integer number (6395893).

Almost surely, 2^21928772 is an apocalyptic number.

It is an amenable number.

21928772 is a deficient number, since it is larger than the sum of its proper divisors (16446586).

21928772 is a wasteful number, since it uses less digits than its factorization.

21928772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5482197 (or 5482195 counting only the distinct ones).

The product of its digits is 28224, while the sum is 38.

The square root of 21928772 is about 4682.8166737552. The cubic root of 21928772 is about 279.9012066431.

The spelling of 21928772 in words is "twenty-one million, nine hundred twenty-eight thousand, seven hundred seventy-two".