21663270 has 48 divisors (see below), whose sum is σ = 59641920. Its totient is φ = 5436672.

The previous prime is 21663251. The next prime is 21663277. The reversal of 21663270 is 7236612.

It is a happy number.

21663270 is a `hidden beast` number, since 21 + 6 + 632 + 7 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21663277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5550 + ... + 8609.

It is an arithmetic number, because the mean of its divisors is an integer number (1242540).

Almost surely, 2^21663270 is an apocalyptic number.

21663270 is an abundant number, since it is smaller than the sum of its proper divisors (37978650).

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

21663270 is a wasteful number, since it uses less digits than its factorization.

21663270 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14189 (or 14186 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 21663270 is about 4654.3818064271. The cubic root of 21663270 is about 278.7669846944.

Adding to 21663270 its reverse (7236612), we get a palindrome (28899882).

The spelling of 21663270 in words is "twenty-one million, six hundred sixty-three thousand, two hundred seventy".