21012102078 has 64 divisors (see below), whose sum is σ = 46585324800. Its totient is φ = 6265244160.

The previous prime is 21012102077. The next prime is 21012102103. The reversal of 21012102078 is 87020121012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012102077) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1026528 + ... + 1046796.

It is an arithmetic number, because the mean of its divisors is an integer number (727895700).

Almost surely, 2^21012102078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21012102078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23292662400).

21012102078 is an abundant number, since it is smaller than the sum of its proper divisors (25573222722).

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

21012102078 is a wasteful number, since it uses less digits than its factorization.

21012102078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20537.

The product of its (nonzero) digits is 448, while the sum is 24.

The spelling of 21012102078 in words is "twenty-one billion, twelve million, one hundred two thousand, seventy-eight".