21660226 has 16 divisors (see below), whose sum is σ = 37257984. Its totient is φ = 9251424.

The previous prime is 21660211. The next prime is 21660239. The reversal of 21660226 is 62206612.

It is a self number, because there is not a number n which added to its sum of digits gives 21660226.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1911 + ... + 6853.

It is an arithmetic number, because the mean of its divisors is an integer number (2328624).

Almost surely, 2^21660226 is an apocalyptic number.

21660226 is a deficient number, since it is larger than the sum of its proper divisors (15597758).

21660226 is a wasteful number, since it uses less digits than its factorization.

21660226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5265.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21660226 is about 4654.0547912546. The cubic root of 21660226 is about 278.7539271635.

Adding to 21660226 its reverse (62206612), we get a palindrome (83866838).

The spelling of 21660226 in words is "twenty-one million, six hundred sixty thousand, two hundred twenty-six".