21878101 has 16 divisors (see below), whose sum is σ = 26460160. Its totient is φ = 17670960.

The previous prime is 21878089. The next prime is 21878111. The reversal of 21878101 is 10187812.

It is a cyclic number.

It is not a de Polignac number, because 21878101 - 2¹¹ = 21876053 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 21878101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21878111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35740 + ... + 36346.

It is an arithmetic number, because the mean of its divisors is an integer number (1653760).

Almost surely, 2^21878101 is an apocalyptic number.

21878101 is the 2701-st hex number.

It is an amenable number.

21878101 is a deficient number, since it is larger than the sum of its proper divisors (4582059).

21878101 is a wasteful number, since it uses less digits than its factorization.

21878101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 904.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21878101 is about 4677.4032325640. The cubic root of 21878101 is about 279.6854503413.

The spelling of 21878101 in words is "twenty-one million, eight hundred seventy-eight thousand, one hundred one".