21551266 has 16 divisors (see below), whose sum is σ = 35632800. Its totient is φ = 9694080.

The previous prime is 21551251. The next prime is 21551267. The reversal of 21551266 is 66215512.

It is a super-3 number, since 3×21551266³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21551267) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2916 + ... + 7183.

It is an arithmetic number, because the mean of its divisors is an integer number (2227050).

Almost surely, 2^21551266 is an apocalyptic number.

21551266 is a deficient number, since it is larger than the sum of its proper divisors (14081534).

21551266 is a wasteful number, since it uses less digits than its factorization.

21551266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10209.

The product of its digits is 3600, while the sum is 28.

The square root of 21551266 is about 4642.3341111988. The cubic root of 21551266 is about 278.2857249020.

Adding to 21551266 its reverse (66215512), we get a palindrome (87766778).

The spelling of 21551266 in words is "twenty-one million, five hundred fifty-one thousand, two hundred sixty-six".