21218870 has 16 divisors (see below), whose sum is σ = 38391408. Its totient is φ = 8443680.

The previous prime is 21218863. The next prime is 21218887. The reversal of 21218870 is 7881212.

It is a super-3 number, since 3×21218870³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3416 + ... + 7355.

It is an arithmetic number, because the mean of its divisors is an integer number (2399463).

Almost surely, 2^21218870 is an apocalyptic number.

21218870 is a deficient number, since it is larger than the sum of its proper divisors (17172538).

21218870 is a wasteful number, since it uses less digits than its factorization.

21218870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10975.

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 21218870 is about 4606.3944685622. The cubic root of 21218870 is about 276.8475921792.

The spelling of 21218870 in words is "twenty-one million, two hundred eighteen thousand, eight hundred seventy".