21355108878 has 16 divisors (see below), whose sum is σ = 42711702480. Its totient is φ = 7118122176.

The previous prime is 21355108871. The next prime is 21355108883. The reversal of 21355108878 is 87880155312.

21355108878 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×21355108878³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355108871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 233868 + ... + 312096.

It is an arithmetic number, because the mean of its divisors is an integer number (2669481405).

Almost surely, 2^21355108878 is an apocalyptic number.

21355108878 is an abundant number, since it is smaller than the sum of its proper divisors (21356593602).

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

21355108878 is a wasteful number, since it uses less digits than its factorization.

21355108878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123731.

The product of its (nonzero) digits is 537600, while the sum is 48.

The spelling of 21355108878 in words is "twenty-one billion, three hundred fifty-five million, one hundred eight thousand, eight hundred seventy-eight".