891650128121 has 4 divisors (see below), whose sum is σ = 891714257232. Its totient is φ = 891585999012.

The previous prime is 891650128111. The next prime is 891650128133. The reversal of 891650128121 is 121821056198.

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.

It is a cyclic number.

It is not a de Polignac number, because 891650128121 - 2¹⁰ = 891650127097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (891650128111) 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, 32043695 + ... + 32071508.

It is an arithmetic number, because the mean of its divisors is an integer number (222928564308).

Almost surely, 2^891650128121 is an apocalyptic number.

It is an amenable number.

891650128121 is a deficient number, since it is larger than the sum of its proper divisors (64129111).

891650128121 is a wasteful number, since it uses less digits than its factorization.

891650128121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64129110.

The product of its (nonzero) digits is 69120, while the sum is 44.

The spelling of 891650128121 in words is "eight hundred ninety-one billion, six hundred fifty million, one hundred twenty-eight thousand, one hundred twenty-one".