21109285978 has 16 divisors (see below), whose sum is σ = 34550195904. Its totient is φ = 9592983360.

The previous prime is 21109285963. The next prime is 21109285997. The reversal of 21109285978 is 87958290112.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4575 + ... + 205522.

It is an arithmetic number, because the mean of its divisors is an integer number (2159387244).

Almost surely, 2^21109285978 is an apocalyptic number.

21109285978 is a deficient number, since it is larger than the sum of its proper divisors (13440909926).

21109285978 is a wasteful number, since it uses less digits than its factorization.

21109285978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214677.

The product of its (nonzero) digits is 725760, while the sum is 52.

The spelling of 21109285978 in words is "twenty-one billion, one hundred nine million, two hundred eighty-five thousand, nine hundred seventy-eight".