21170172 has 24 divisors (see below), whose sum is σ = 50208592. Its totient is φ = 6940800.

The previous prime is 21170159. The next prime is 21170207. The reversal of 21170172 is 27107112.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13729 + ... + 15192.

Almost surely, 2^21170172 is an apocalyptic number.

It is an amenable number.

21170172 is an abundant number, since it is smaller than the sum of its proper divisors (29038420).

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

21170172 is a wasteful number, since it uses less digits than its factorization.

21170172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28989 (or 28987 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 21.

The square root of 21170172 is about 4601.1055193290. The cubic root of 21170172 is about 276.6356385261.

Adding to 21170172 its reverse (27107112), we get a palindrome (48277284).

The spelling of 21170172 in words is "twenty-one million, one hundred seventy thousand, one hundred seventy-two".