991501541 has 4 divisors (see below), whose sum is σ = 991707072. Its totient is φ = 991296012.

The previous prime is 991501531. The next prime is 991501559. The reversal of 991501541 is 145105199.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991501541 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991501531) 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, 95351 + ... + 105236.

It is an arithmetic number, because the mean of its divisors is an integer number (247926768).

Almost surely, 2^991501541 is an apocalyptic number.

It is an amenable number.

991501541 is a deficient number, since it is larger than the sum of its proper divisors (205531).

991501541 is a wasteful number, since it uses less digits than its factorization.

991501541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205530.

The product of its (nonzero) digits is 8100, while the sum is 35.

The square root of 991501541 is about 31488.1174572250. The cubic root of 991501541 is about 997.1591173617.

The spelling of 991501541 in words is "nine hundred ninety-one million, five hundred one thousand, five hundred forty-one".