21115772 has 6 divisors (see below), whose sum is σ = 36952608. Its totient is φ = 10557884.

The previous prime is 21115753. The next prime is 21115777. The reversal of 21115772 is 27751112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2639468 + ... + 2639475.

It is an arithmetic number, because the mean of its divisors is an integer number (6158768).

Almost surely, 2^21115772 is an apocalyptic number.

It is an amenable number.

21115772 is a deficient number, since it is larger than the sum of its proper divisors (15836836).

21115772 is a wasteful number, since it uses less digits than its factorization.

21115772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5278947 (or 5278945 counting only the distinct ones).

The product of its digits is 980, while the sum is 26.

The square root of 21115772 is about 4595.1900940005. The cubic root of 21115772 is about 276.3984827236.

Adding to 21115772 its reverse (27751112), we get a palindrome (48866884).

The spelling of 21115772 in words is "twenty-one million, one hundred fifteen thousand, seven hundred seventy-two".