21572170 has 16 divisors (see below), whose sum is σ = 39489120. Its totient is φ = 8482384.

The previous prime is 21572141. The next prime is 21572179. The reversal of 21572170 is 7127512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21572179) 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, 17692 + ... + 18871.

It is an arithmetic number, because the mean of its divisors is an integer number (2468070).

Almost surely, 2^21572170 is an apocalyptic number.

21572170 is a deficient number, since it is larger than the sum of its proper divisors (17916950).

21572170 is a wasteful number, since it uses less digits than its factorization.

21572170 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36629.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21572170 is about 4644.5850191379. The cubic root of 21572170 is about 278.3756717440.

Adding to 21572170 its reverse (7127512), we get a palindrome (28699682).

The spelling of 21572170 in words is "twenty-one million, five hundred seventy-two thousand, one hundred seventy".