998997791 has 4 divisors (see below), whose sum is σ = 1089815784. Its totient is φ = 908179800.

The previous prime is 998997787. The next prime is 998997803. The reversal of 998997791 is 197799899.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 998997791 - 2² = 998997787 is a prime.

It is a super-3 number, since 3×998997791³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998997731) 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, 45408980 + ... + 45409001.

It is an arithmetic number, because the mean of its divisors is an integer number (272453946).

Almost surely, 2^998997791 is an apocalyptic number.

998997791 is a deficient number, since it is larger than the sum of its proper divisors (90817993).

998997791 is a wasteful number, since it uses less digits than its factorization.

998997791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90817992.

The product of its digits is 23147208, while the sum is 68.

The square root of 998997791 is about 31606.9263137054. The cubic root of 998997791 is about 999.6658186686.

The spelling of 998997791 in words is "nine hundred ninety-eight million, nine hundred ninety-seven thousand, seven hundred ninety-one".