21870356 has 12 divisors (see below), whose sum is σ = 38922240. Its totient is φ = 10749720.

The previous prime is 21870353. The next prime is 21870389. The reversal of 21870356 is 65307812.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21870353) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 46100 + ... + 46571.

It is an arithmetic number, because the mean of its divisors is an integer number (3243520).

Almost surely, 2^21870356 is an apocalyptic number.

It is an amenable number.

21870356 is a deficient number, since it is larger than the sum of its proper divisors (17051884).

21870356 is a wasteful number, since it uses less digits than its factorization.

21870356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92734 (or 92732 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21870356 is about 4676.5752426322. The cubic root of 21870356 is about 279.6524429141.

The spelling of 21870356 in words is "twenty-one million, eight hundred seventy thousand, three hundred fifty-six".