1994021801 has 4 divisors (see below), whose sum is σ = 1995302400. Its totient is φ = 1992741204.

The previous prime is 1994021789. The next prime is 1994021807. The reversal of 1994021801 is 1081204991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1081204991 = 15313 ⋅70607.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1994021801 is a prime.

It is a super-2 number, since 2×1994021801² = 7952245885726567202, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1994021807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 637961 + ... + 641078.

It is an arithmetic number, because the mean of its divisors is an integer number (498825600).

Almost surely, 2^1994021801 is an apocalyptic number.

It is an amenable number.

1994021801 is a deficient number, since it is larger than the sum of its proper divisors (1280599).

1994021801 is a wasteful number, since it uses less digits than its factorization.

1994021801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280598.

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 1994021801 is about 44654.4712318935. The cubic root of 1994021801 is about 1258.6644539051.

The spelling of 1994021801 in words is "one billion, nine hundred ninety-four million, twenty-one thousand, eight hundred one".