1999800155 has 4 divisors (see below), whose sum is σ = 2399760192. Its totient is φ = 1599840120.

The previous prime is 1999800139. The next prime is 1999800169. The reversal of 1999800155 is 5510089991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5510089991 = 7 ⋅787155713.

It is not a de Polignac number, because 1999800155 - 2⁴ = 1999800139 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 199980011 + ... + 199980020.

It is an arithmetic number, because the mean of its divisors is an integer number (599940048).

Almost surely, 2^1999800155 is an apocalyptic number.

1999800155 is a deficient number, since it is larger than the sum of its proper divisors (399960037).

1999800155 is an equidigital number, since it uses as much as digits as its factorization.

1999800155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399960036.

The product of its (nonzero) digits is 145800, while the sum is 47.

The square root of 1999800155 is about 44719.1251591531. The cubic root of 1999800155 is about 1259.8790836767.

The spelling of 1999800155 in words is "one billion, nine hundred ninety-nine million, eight hundred thousand, one hundred fifty-five".