21131331078 has 96 divisors (see below), whose sum is σ = 50441311872. Its totient is φ = 5849625600.

The previous prime is 21131331077. The next prime is 21131331113. The reversal of 21131331078 is 87013313112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131331073) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1072173 + ... + 1091703.

It is an arithmetic number, because the mean of its divisors is an integer number (525430332).

Almost surely, 2^21131331078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21131331078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25220655936).

21131331078 is an abundant number, since it is smaller than the sum of its proper divisors (29309980794).

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

21131331078 is a wasteful number, since it uses less digits than its factorization.

21131331078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19670 (or 19657 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 30.

The spelling of 21131331078 in words is "twenty-one billion, one hundred thirty-one million, three hundred thirty-one thousand, seventy-eight".