851988991906 has 16 divisors (see below), whose sum is σ = 1376338268088. Its totient is φ = 393211872000.

The previous prime is 851988991883. The next prime is 851988991957. The reversal of 851988991906 is 609199889158.

It can be written as a sum of positive squares in 4 ways, for example, as 474328351225 + 377660640681 = 688715^2 + 614541^2 .

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, 198136 + ... + 1320316.

Almost surely, 2^851988991906 is an apocalyptic number.

851988991906 is a deficient number, since it is larger than the sum of its proper divisors (524349276182).

851988991906 is a wasteful number, since it uses less digits than its factorization.

851988991906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1151397.

The product of its (nonzero) digits is 100776960, while the sum is 73.

The spelling of 851988991906 in words is "eight hundred fifty-one billion, nine hundred eighty-eight million, nine hundred ninety-one thousand, nine hundred six".