991904451136 has 21 divisors (see below), whose sum is σ = 1968326205961. Its totient is φ = 495948241792.

The previous prime is 991904451107. The next prime is 991904451173. The reversal of 991904451136 is 631154409199.

The square root of 991904451136 is 995944.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 453359822400 + 538544628736 = 673320^2 + 733856^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 7905306 + ... + 8029798.

Almost surely, 2^991904451136 is an apocalyptic number.

991904451136 is the 995944-th square number.

It is an amenable number.

991904451136 is a deficient number, since it is larger than the sum of its proper divisors (976421754825).

991904451136 is an frugal number, since it uses more digits than its factorization.

991904451136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248998 (or 124495 counting only the distinct ones).

The product of its (nonzero) digits is 1049760, while the sum is 52.

The spelling of 991904451136 in words is "nine hundred ninety-one billion, nine hundred four million, four hundred fifty-one thousand, one hundred thirty-six".