21431066 has 16 divisors (see below), whose sum is σ = 33488640. Its totient is φ = 10276560.

The previous prime is 21431063. The next prime is 21431099. The reversal of 21431066 is 66013412.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21431063) 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, 3215 + ... + 7293.

It is an arithmetic number, because the mean of its divisors is an integer number (2093040).

Almost surely, 2^21431066 is an apocalyptic number.

21431066 is a deficient number, since it is larger than the sum of its proper divisors (12057574).

21431066 is a wasteful number, since it uses less digits than its factorization.

21431066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4189.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21431066 is about 4629.3699355312. The cubic root of 21431066 is about 277.7673899167.

Adding to 21431066 its reverse (66013412), we get a palindrome (87444478).

The spelling of 21431066 in words is "twenty-one million, four hundred thirty-one thousand, sixty-six".