21640226 has 4 divisors (see below), whose sum is σ = 32460342. Its totient is φ = 10820112.

The previous prime is 21640219. The next prime is 21640231. The reversal of 21640226 is 62204612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 12967201 + 8673025 = 3601^2 + 2945^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5410055 + ... + 5410058.

Almost surely, 2^21640226 is an apocalyptic number.

21640226 is a deficient number, since it is larger than the sum of its proper divisors (10820116).

21640226 is a wasteful number, since it uses less digits than its factorization.

21640226 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10820115.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 21640226 is about 4651.9056310291. The cubic root of 21640226 is about 278.6681048004.

Adding to 21640226 its reverse (62204612), we get a palindrome (83844838).

The spelling of 21640226 in words is "twenty-one million, six hundred forty thousand, two hundred twenty-six".