22087981 has 12 divisors (see below), whose sum is σ = 24491232. Its totient is φ = 19878848.

The previous prime is 22087969. The next prime is 22087999. The reversal of 22087981 is 18978022.

22087981 is a nontrivial binomial coefficient, being equal to C(6647, 2).

It is not a de Polignac number, because 22087981 - 2¹¹ = 22085933 is a prime.

It is a super-2 number, since 2×22087981² = 975757809312722, which contains 22 as substring.

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 22087981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22087951) 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, 4986 + ... + 8308.

It is an arithmetic number, because the mean of its divisors is an integer number (2040936).

Almost surely, 2^22087981 is an apocalyptic number.

22087981 is the 6646-th triangular number.

22087981 is the 2216-th centered nonagonal number.

It is an amenable number.

22087981 is a deficient number, since it is larger than the sum of its proper divisors (2403251).

22087981 is a wasteful number, since it uses less digits than its factorization.

22087981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3380 (or 3363 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 22087981 is about 4699.7852078579. The cubic root of 22087981 is about 280.5769608229.

The spelling of 22087981 in words is "twenty-two million, eighty-seven thousand, nine hundred eighty-one".