991638154 has 8 divisors (see below), whose sum is σ = 1601877060. Its totient is φ = 457679136.

The previous prime is 991638133. The next prime is 991638157. The reversal of 991638154 is 451836199.

991638154 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 991305225 + 332929 = 31485^2 + 577^2 .

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

It is not an unprimeable number, because it can be changed into a prime (991638157) 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, 19069939 + ... + 19069990.

Almost surely, 2^991638154 is an apocalyptic number.

991638154 is a deficient number, since it is larger than the sum of its proper divisors (610238906).

991638154 is a wasteful number, since it uses less digits than its factorization.

991638154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38139944.

The product of its digits is 233280, while the sum is 46.

The square root of 991638154 is about 31490.2866611277. The cubic root of 991638154 is about 997.2049127662.

The spelling of 991638154 in words is "nine hundred ninety-one million, six hundred thirty-eight thousand, one hundred fifty-four".