1991217134 has 16 divisors (see below), whose sum is σ = 3183003648. Its totient is φ = 932058072.

The previous prime is 1991217133. The next prime is 1991217167. The reversal of 1991217134 is 4317121991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991217133) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 458342 + ... + 462665.

It is an arithmetic number, because the mean of its divisors is an integer number (198937728).

Almost surely, 2^1991217134 is an apocalyptic number.

1991217134 is a deficient number, since it is larger than the sum of its proper divisors (1191786514).

1991217134 is a wasteful number, since it uses less digits than its factorization.

1991217134 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 921079.

The product of its digits is 13608, while the sum is 38.

The square root of 1991217134 is about 44623.0560809096. The cubic root of 1991217134 is about 1258.0740573106.

The spelling of 1991217134 in words is "one billion, nine hundred ninety-one million, two hundred seventeen thousand, one hundred thirty-four".