1998551890 has 32 divisors (see below), whose sum is σ = 3632999040. Its totient is φ = 791539584.

The previous prime is 1998551881. The next prime is 1998551897. The reversal of 1998551890 is 981558991.

It is not an unprimeable number, because it can be changed into a prime (1998551897) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 599769 + ... + 603091.

It is an arithmetic number, because the mean of its divisors is an integer number (113531220).

Almost surely, 2^1998551890 is an apocalyptic number.

1998551890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1998551890 is a deficient number, since it is larger than the sum of its proper divisors (1634447150).

1998551890 is a wasteful number, since it uses less digits than its factorization.

1998551890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3906.

The product of its (nonzero) digits is 1166400, while the sum is 55.

The square root of 1998551890 is about 44705.1662562617. The cubic root of 1998551890 is about 1259.6168924289.

The spelling of 1998551890 in words is "one billion, nine hundred ninety-eight million, five hundred fifty-one thousand, eight hundred ninety".