21388870 has 16 divisors (see below), whose sum is σ = 40526640. Its totient is φ = 8105184.

The previous prime is 21388867. The next prime is 21388883. The reversal of 21388870 is 7888312.

It is a zygodrome in base 9.

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, 56097 + ... + 56476.

It is an arithmetic number, because the mean of its divisors is an integer number (2532915).

Almost surely, 2^21388870 is an apocalyptic number.

21388870 is a deficient number, since it is larger than the sum of its proper divisors (19137770).

21388870 is a wasteful number, since it uses less digits than its factorization.

21388870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112599.

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 21388870 is about 4624.8102663785. The cubic root of 21388870 is about 277.5849697864.

The spelling of 21388870 in words is "twenty-one million, three hundred eighty-eight thousand, eight hundred seventy".