1998257657 has 8 divisors (see below), whose sum is σ = 2183446560. Its totient is φ = 1813656960.

The previous prime is 1998257621. The next prime is 1998257669. The reversal of 1998257657 is 7567528991.

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 1998257657 - 2³⁰ = 924515833 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1998257596 and 1998257605.

It is not an unprimeable number, because it can be changed into a prime (1998257857) 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, 139928 + ... + 153545.

It is an arithmetic number, because the mean of its divisors is an integer number (272930820).

Almost surely, 2^1998257657 is an apocalyptic number.

It is an amenable number.

1998257657 is a deficient number, since it is larger than the sum of its proper divisors (185188903).

1998257657 is a wasteful number, since it uses less digits than its factorization.

1998257657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294103.

The product of its digits is 9525600, while the sum is 59.

The square root of 1998257657 is about 44701.8753186038. The cubic root of 1998257657 is about 1259.5550744949. Note that the first 3 decimals are identical.

The spelling of 1998257657 in words is "one billion, nine hundred ninety-eight million, two hundred fifty-seven thousand, six hundred fifty-seven".