19980101 has 4 divisors (see below), whose sum is σ = 20669100. Its totient is φ = 19291104.

The previous prime is 19980091. The next prime is 19980113. The reversal of 19980101 is 10108991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10108991 = 227 ⋅44533.

It can be written as a sum of positive squares in 2 ways, for example, as 7695076 + 12285025 = 2774^2 + 3505^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19980101 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 688969 = 19980101 / (1 + 9 + 9 + 8 + 0 + 1 + 0 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19983101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 344456 + ... + 344513.

It is an arithmetic number, because the mean of its divisors is an integer number (5167275).

Almost surely, 2^19980101 is an apocalyptic number.

It is an amenable number.

19980101 is a deficient number, since it is larger than the sum of its proper divisors (688999).

19980101 is an equidigital number, since it uses as much as digits as its factorization.

19980101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688998.

The product of its (nonzero) digits is 648, while the sum is 29.

The square root of 19980101 is about 4469.9106255047. The cubic root of 19980101 is about 271.3517081264.

The spelling of 19980101 in words is "nineteen million, nine hundred eighty thousand, one hundred one".