855578642921 has 4 divisors (see below), whose sum is σ = 857214549072. Its totient is φ = 853942736772.

The previous prime is 855578642917. The next prime is 855578642927. The reversal of 855578642921 is 129246875558.

855578642921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 129246875558 = 2 ⋅64623437779.

It is a cyclic number.

It is not a de Polignac number, because 855578642921 - 2² = 855578642917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (855578642927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 817952291 + ... + 817953336.

It is an arithmetic number, because the mean of its divisors is an integer number (214303637268).

Almost surely, 2^855578642921 is an apocalyptic number.

It is an amenable number.

855578642921 is a deficient number, since it is larger than the sum of its proper divisors (1635906151).

855578642921 is a wasteful number, since it uses less digits than its factorization.

855578642921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1635906150.

The product of its digits is 48384000, while the sum is 62.

The spelling of 855578642921 in words is "eight hundred fifty-five billion, five hundred seventy-eight million, six hundred forty-two thousand, nine hundred twenty-one".