22120991 has 4 divisors (see below), whose sum is σ = 22249032. Its totient is φ = 21992952.

The previous prime is 22120957. The next prime is 22121003. The reversal of 22120991 is 19902122.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-22120991 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 22120991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22120951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63761 + ... + 64106.

It is an arithmetic number, because the mean of its divisors is an integer number (5562258).

Almost surely, 2^22120991 is an apocalyptic number.

22120991 is a deficient number, since it is larger than the sum of its proper divisors (128041).

22120991 is a wasteful number, since it uses less digits than its factorization.

22120991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128040.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 22120991 is about 4703.2957593585. The cubic root of 22120991 is about 280.7166632766.

It can be divided in two parts, 221 and 20991, that added together give a palindrome (21212).

The spelling of 22120991 in words is "twenty-two million, one hundred twenty thousand, nine hundred ninety-one".