905978834221 has 4 divisors (see below), whose sum is σ = 905980739932. Its totient is φ = 905976928512.

The previous prime is 905978834219. The next prime is 905978834239. The reversal of 905978834221 is 122438879509.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 449719113321 + 456259720900 = 670611^2 + 675470^2 .

It is a cyclic number.

It is not a de Polignac number, because 905978834221 - 2¹ = 905978834219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (905978834281) 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, 410125 + ... + 1407181.

It is an arithmetic number, because the mean of its divisors is an integer number (226495184983).

Almost surely, 2^905978834221 is an apocalyptic number.

It is an amenable number.

905978834221 is a deficient number, since it is larger than the sum of its proper divisors (1905711).

905978834221 is an equidigital number, since it uses as much as digits as its factorization.

905978834221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1905710.

The product of its (nonzero) digits is 8709120, while the sum is 58.

The spelling of 905978834221 in words is "nine hundred five billion, nine hundred seventy-eight million, eight hundred thirty-four thousand, two hundred twenty-one".