22156991 has 4 divisors (see below), whose sum is σ = 22221192. Its totient is φ = 22092792.

The previous prime is 22156987. The next prime is 22156993. The reversal of 22156991 is 19965122.

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

It is a cyclic number.

It is not a de Polignac number, because 22156991 - 2² = 22156987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22156993) 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, 31580 + ... + 32273.

It is an arithmetic number, because the mean of its divisors is an integer number (5555298).

Almost surely, 2^22156991 is an apocalyptic number.

22156991 is a deficient number, since it is larger than the sum of its proper divisors (64201).

22156991 is an equidigital number, since it uses as much as digits as its factorization.

22156991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64200.

The product of its digits is 9720, while the sum is 35.

The square root of 22156991 is about 4707.1213071260. The cubic root of 22156991 is about 280.8688614418.

The spelling of 22156991 in words is "twenty-two million, one hundred fifty-six thousand, nine hundred ninety-one".