1998556709 has 8 divisors (see below), whose sum is σ = 2061143040. Its totient is φ = 1936702656.

The previous prime is 1998556643. The next prime is 1998556711. The reversal of 1998556709 is 9076558991.

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 1998556709 - 2²⁴ = 1981779493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998556789) 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, 177524 + ... + 188445.

It is an arithmetic number, because the mean of its divisors is an integer number (257642880).

Almost surely, 2^1998556709 is an apocalyptic number.

It is an amenable number.

1998556709 is a deficient number, since it is larger than the sum of its proper divisors (62586331).

1998556709 is a wasteful number, since it uses less digits than its factorization.

1998556709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366139.

The product of its (nonzero) digits is 6123600, while the sum is 59.

The square root of 1998556709 is about 44705.2201538031. The cubic root of 1998556709 is about 1259.6179048434.

The spelling of 1998556709 in words is "one billion, nine hundred ninety-eight million, five hundred fifty-six thousand, seven hundred nine".