21773791 has 12 divisors (see below), whose sum is σ = 24822120. Its totient is φ = 19038240.

The previous prime is 21773789. The next prime is 21773803. The reversal of 21773791 is 19737712.

It is not a de Polignac number, because 21773791 - 2¹ = 21773789 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21773791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21773701) 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, 180 + ... + 6601.

It is an arithmetic number, because the mean of its divisors is an integer number (2068510).

Almost surely, 2^21773791 is an apocalyptic number.

21773791 is a deficient number, since it is larger than the sum of its proper divisors (3048329).

21773791 is a wasteful number, since it uses less digits than its factorization.

21773791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6826 (or 6813 counting only the distinct ones).

The product of its digits is 18522, while the sum is 37.

The square root of 21773791 is about 4666.2394923536. The cubic root of 21773791 is about 279.2402490326.

The spelling of 21773791 in words is "twenty-one million, seven hundred seventy-three thousand, seven hundred ninety-one".