21278078385 has 8 divisors (see below), whose sum is σ = 34044925440. Its totient is φ = 11348308464.

The previous prime is 21278078351. The next prime is 21278078387. The reversal of 21278078385 is 58387087212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21278078385 - 2³⁰ = 20204336561 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21278078387) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 709269265 + ... + 709269294.

It is an arithmetic number, because the mean of its divisors is an integer number (4255615680).

Almost surely, 2^21278078385 is an apocalyptic number.

It is an amenable number.

21278078385 is a deficient number, since it is larger than the sum of its proper divisors (12766847055).

21278078385 is a wasteful number, since it uses less digits than its factorization.

21278078385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1418538567.

The product of its (nonzero) digits is 1505280, while the sum is 51.

The spelling of 21278078385 in words is "twenty-one billion, two hundred seventy-eight million, seventy-eight thousand, three hundred eighty-five".