21367867878 has 80 divisors (see below), whose sum is σ = 54767860224. Its totient is φ = 6099747120.

The previous prime is 21367867861. The next prime is 21367867879. The reversal of 21367867878 is 87876876312.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21367867879) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1388301 + ... + 1403607.

Almost surely, 2^21367867878 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21367867878, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27383930112).

21367867878 is an abundant number, since it is smaller than the sum of its proper divisors (33399992346).

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

21367867878 is a wasteful number, since it uses less digits than its factorization.

21367867878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16559 (or 16550 counting only the distinct ones).

The product of its digits is 37933056, while the sum is 63.

The spelling of 21367867878 in words is "twenty-one billion, three hundred sixty-seven million, eight hundred sixty-seven thousand, eight hundred seventy-eight".