21520170 has 48 divisors (see below), whose sum is σ = 63947520. Its totient is φ = 4918752.

The previous prime is 21520159. The next prime is 21520189. The reversal of 21520170 is 7102512.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16450 + ... + 17709.

It is an arithmetic number, because the mean of its divisors is an integer number (1332240).

Almost surely, 2^21520170 is an apocalyptic number.

21520170 is an abundant number, since it is smaller than the sum of its proper divisors (42427350).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21520170 is a wasteful number, since it uses less digits than its factorization.

21520170 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34179 (or 34176 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21520170 is about 4638.9837249122. The cubic root of 21520170 is about 278.1518157034.

Adding to 21520170 its reverse (7102512), we get a palindrome (28622682).

The spelling of 21520170 in words is "twenty-one million, five hundred twenty thousand, one hundred seventy".