22191981 has 16 divisors (see below), whose sum is σ = 35596800. Its totient is φ = 12013488.

The previous prime is 22191979. The next prime is 22191991. The reversal of 22191981 is 18919122.

It is not a de Polignac number, because 22191981 - 2¹ = 22191979 is a prime.

It is a super-2 number, since 2×22191981² = 984968041408722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22191901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27411 + ... + 28208.

It is an arithmetic number, because the mean of its divisors is an integer number (2224800).

Almost surely, 2^22191981 is an apocalyptic number.

22191981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

22191981 is a deficient number, since it is larger than the sum of its proper divisors (13404819).

22191981 is a wasteful number, since it uses less digits than its factorization.

22191981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55648.

The product of its digits is 2592, while the sum is 33.

The square root of 22191981 is about 4710.8365499134. The cubic root of 22191981 is about 281.0166316992.

The spelling of 22191981 in words is "twenty-two million, one hundred ninety-one thousand, nine hundred eighty-one".