21211170078 has 128 divisors (see below), whose sum is σ = 52254720000. Its totient is φ = 5725939296.

The previous prime is 21211170059. The next prime is 21211170089. The reversal of 21211170078 is 87007111212.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3926023 + ... + 3931421.

It is an arithmetic number, because the mean of its divisors is an integer number (408240000).

Almost surely, 2^21211170078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21211170078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26127360000).

21211170078 is an abundant number, since it is smaller than the sum of its proper divisors (31043549922).

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

21211170078 is a wasteful number, since it uses less digits than its factorization.

21211170078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5531 (or 5517 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 30.

The spelling of 21211170078 in words is "twenty-one billion, two hundred eleven million, one hundred seventy thousand, seventy-eight".