1991091541 has 8 divisors (see below), whose sum is σ = 2061158400. Its totient is φ = 1921118640.

The previous prime is 1991091517. The next prime is 1991091559. The reversal of 1991091541 is 1451901991.

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

It is a cyclic number.

It is not a de Polignac number, because 1991091541 - 2²¹ = 1988994389 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1991091494 and 1991091503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991091511) 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, 21100 + ... + 66538.

It is an arithmetic number, because the mean of its divisors is an integer number (257644800).

Almost surely, 2^1991091541 is an apocalyptic number.

It is an amenable number.

1991091541 is a deficient number, since it is larger than the sum of its proper divisors (70066859).

1991091541 is a wasteful number, since it uses less digits than its factorization.

1991091541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46979.

The product of its (nonzero) digits is 14580, while the sum is 40.

The square root of 1991091541 is about 44621.6487929346. The cubic root of 1991091541 is about 1258.0476063836.

The spelling of 1991091541 in words is "one billion, nine hundred ninety-one million, ninety-one thousand, five hundred forty-one".