21772791 has 12 divisors (see below), whose sum is σ = 31965960. Its totient is φ = 14276880.

The previous prime is 21772787. The next prime is 21772811. The reversal of 21772791 is 19727712.

It is not a de Polignac number, because 21772791 - 2² = 21772787 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21772741) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19281 + ... + 20378.

It is an arithmetic number, because the mean of its divisors is an integer number (2663830).

Almost surely, 2^21772791 is an apocalyptic number.

21772791 is a deficient number, since it is larger than the sum of its proper divisors (10193169).

21772791 is a wasteful number, since it uses less digits than its factorization.

21772791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39726 (or 39723 counting only the distinct ones).

The product of its digits is 12348, while the sum is 36.

The square root of 21772791 is about 4666.1323384576. The cubic root of 21772791 is about 279.2359740991.

The spelling of 21772791 in words is "twenty-one million, seven hundred seventy-two thousand, seven hundred ninety-one".