21258870 has 32 divisors (see below), whose sum is σ = 52669440. Its totient is φ = 5485920.

The previous prime is 21258863. The next prime is 21258871. The reversal of 21258870 is 7885212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21258871) 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 15 ways as a sum of consecutive naturals, for example, 10500 + ... + 12359.

It is an arithmetic number, because the mean of its divisors is an integer number (1645920).

Almost surely, 2^21258870 is an apocalyptic number.

21258870 is an abundant number, since it is smaller than the sum of its proper divisors (31410570).

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

21258870 is a wasteful number, since it uses less digits than its factorization.

21258870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22900.

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 21258870 is about 4610.7342148513. The cubic root of 21258870 is about 277.0214461190.

The spelling of 21258870 in words is "twenty-one million, two hundred fifty-eight thousand, eight hundred seventy".