21017850378 has 48 divisors (see below), whose sum is σ = 49039828704. Its totient is φ = 5987765280.

The previous prime is 21017850361. The next prime is 21017850457. The reversal of 21017850378 is 87305871012.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 993 + ... + 205028.

It is an arithmetic number, because the mean of its divisors is an integer number (1021663098).

Almost surely, 2^21017850378 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21017850378, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24519914352).

21017850378 is an abundant number, since it is smaller than the sum of its proper divisors (28021978326).

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

21017850378 is a wasteful number, since it uses less digits than its factorization.

21017850378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206387 (or 206380 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 42.

The spelling of 21017850378 in words is "twenty-one billion, seventeen million, eight hundred fifty thousand, three hundred seventy-eight".