21888966 has 16 divisors (see below), whose sum is σ = 47757888. Its totient is φ = 6633000.

The previous prime is 21888961. The next prime is 21888973. The reversal of 21888966 is 66988812.

Added to its reverse (66988812) it gives a triangular number (88877778 = T₁₃₃₃₂).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21888961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165760 + ... + 165891.

It is an arithmetic number, because the mean of its divisors is an integer number (2984868).

Almost surely, 2^21888966 is an apocalyptic number.

21888966 is an abundant number, since it is smaller than the sum of its proper divisors (25868922).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21888966 is a wasteful number, since it uses less digits than its factorization.

21888966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331667.

The product of its digits is 331776, while the sum is 48.

The square root of 21888966 is about 4678.5645234409. The cubic root of 21888966 is about 279.7317413718.

Adding to 21888966 its reverse (66988812), we get a triangular number (88877778 = T₁₃₃₃₂).

It can be divided in two parts, 2188896 and 6, that multiplied together give a square (13133376 = 3624²).

The spelling of 21888966 in words is "twenty-one million, eight hundred eighty-eight thousand, nine hundred sixty-six".