21172550 has 24 divisors (see below), whose sum is σ = 45007536. Its totient is φ = 7259040.

The previous prime is 21172537. The next prime is 21172561. The reversal of 21172550 is 5527112.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29897 + ... + 30596.

It is an arithmetic number, because the mean of its divisors is an integer number (1875314).

Almost surely, 2^21172550 is an apocalyptic number.

21172550 is an abundant number, since it is smaller than the sum of its proper divisors (23834986).

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

21172550 is a wasteful number, since it uses less digits than its factorization.

21172550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60512 (or 60507 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21172550 is about 4601.3639282282. The cubic root of 21172550 is about 276.6459961009.

Adding to 21172550 its reverse (5527112), we get a palindrome (26699662).

The spelling of 21172550 in words is "twenty-one million, one hundred seventy-two thousand, five hundred fifty".