21172084 has 12 divisors (see below), whose sum is σ = 37165408. Its totient is φ = 10553400.

The previous prime is 21172057. The next prime is 21172087. The reversal of 21172084 is 48027112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21172087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6672 + ... + 9319.

Almost surely, 2^21172084 is an apocalyptic number.

It is an amenable number.

21172084 is a deficient number, since it is larger than the sum of its proper divisors (15993324).

21172084 is a wasteful number, since it uses less digits than its factorization.

21172084 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16326 (or 16324 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21172084 is about 4601.3132907899. The cubic root of 21172084 is about 276.6439664606.

Adding to 21172084 its reverse (48027112), we get a palindrome (69199196).

The spelling of 21172084 in words is "twenty-one million, one hundred seventy-two thousand, eighty-four".