22001661 has 48 divisors (see below), whose sum is σ = 36661248. Its totient is φ = 12592800.

The previous prime is 22001659. The next prime is 22001669. The reversal of 22001661 is 16610022.

It is a happy number.

22001661 is a `hidden beast` number, since 2 + 2 + 0 + 0 + 1 + 661 = 666.

22001661 is a nontrivial binomial coefficient, being equal to C(6634, 2).

It is not a de Polignac number, because 22001661 - 2¹ = 22001659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22001669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 205570 + ... + 205676.

It is an arithmetic number, because the mean of its divisors is an integer number (763776).

Almost surely, 2^22001661 is an apocalyptic number.

22001661 is the 6633-rd triangular number and also the 3317-th hexagonal number.

It is an amenable number.

22001661 is a deficient number, since it is larger than the sum of its proper divisors (14659587).

22001661 is a wasteful number, since it uses less digits than its factorization.

22001661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222 (or 219 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 22001661 is about 4690.5928196764. The cubic root of 22001661 is about 280.2109846871.

Adding to 22001661 its reverse (16610022), we get a palindrome (38611683).

The spelling of 22001661 in words is "twenty-two million, one thousand, six hundred sixty-one".