21572205 has 16 divisors (see below), whose sum is σ = 34603200. Its totient is φ = 11475968.

The previous prime is 21572179. The next prime is 21572209. The reversal of 21572205 is 50227512.

It is a cyclic number.

It is not a de Polignac number, because 21572205 - 2⁶ = 21572141 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21572209) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5134 + ... + 8336.

It is an arithmetic number, because the mean of its divisors is an integer number (2162700).

Almost surely, 2^21572205 is an apocalyptic number.

It is an amenable number.

21572205 is a deficient number, since it is larger than the sum of its proper divisors (13030995).

21572205 is a wasteful number, since it uses less digits than its factorization.

21572205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3660.

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21572205 is about 4644.5887869649. The cubic root of 21572205 is about 278.3758222951.

Adding to 21572205 its reverse (50227512), we get a palindrome (71799717).

The spelling of 21572205 in words is "twenty-one million, five hundred seventy-two thousand, two hundred five".