998777661 has 32 divisors (see below), whose sum is σ = 1596672000. Its totient is φ = 543264960.

The previous prime is 998777653. The next prime is 998777699. The reversal of 998777661 is 166777899.

It is a happy number.

998777661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 998777661 - 2³ = 998777653 is a prime.

It is a super-2 number, since 2×998777661² = 1995113632225261842, which contains 22 as substring.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 998777595 and 998777604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998777861) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 31690 + ... + 54788.

It is an arithmetic number, because the mean of its divisors is an integer number (49896000).

Almost surely, 2^998777661 is an apocalyptic number.

It is an amenable number.

998777661 is a deficient number, since it is larger than the sum of its proper divisors (597894339).

998777661 is a wasteful number, since it uses less digits than its factorization.

998777661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23209.

The product of its digits is 8001504, while the sum is 60.

The square root of 998777661 is about 31603.4438155085. The cubic root of 998777661 is about 999.5923875413.

The spelling of 998777661 in words is "nine hundred ninety-eight million, seven hundred seventy-seven thousand, six hundred sixty-one".