21255670 has 8 divisors (see below), whose sum is σ = 38260224. Its totient is φ = 8502264.

The previous prime is 21255653. The next prime is 21255673. The reversal of 21255670 is 7655212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255673) 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, 1062774 + ... + 1062793.

It is an arithmetic number, because the mean of its divisors is an integer number (4782528).

Almost surely, 2^21255670 is an apocalyptic number.

21255670 is a deficient number, since it is larger than the sum of its proper divisors (17004554).

21255670 is a wasteful number, since it uses less digits than its factorization.

21255670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2125574.

The product of its (nonzero) digits is 4200, while the sum is 28.

The square root of 21255670 is about 4610.3871854759. The cubic root of 21255670 is about 277.0075458331.

The spelling of 21255670 in words is "twenty-one million, two hundred fifty-five thousand, six hundred seventy".