991986501 has 8 divisors (see below), whose sum is σ = 1442889504. Its totient is φ = 601203920.

The previous prime is 991986467. The next prime is 991986503. The reversal of 991986501 is 105689199.

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 991986501 - 2¹¹ = 991984453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991986503) 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, 15030066 + ... + 15030131.

It is an arithmetic number, because the mean of its divisors is an integer number (180361188).

Almost surely, 2^991986501 is an apocalyptic number.

It is an amenable number.

991986501 is a deficient number, since it is larger than the sum of its proper divisors (450903003).

991986501 is a wasteful number, since it uses less digits than its factorization.

991986501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30060211.

The product of its (nonzero) digits is 174960, while the sum is 48.

The square root of 991986501 is about 31495.8171984789. The cubic root of 991986501 is about 997.3216666012.

The spelling of 991986501 in words is "nine hundred ninety-one million, nine hundred eighty-six thousand, five hundred one".