1201661999 has 4 divisors (see below), whose sum is σ = 1201812960. Its totient is φ = 1201511040.

The previous prime is 1201661977. The next prime is 1201662023. The reversal of 1201661999 is 9991661021.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9991661021 = 157 ⋅63641153.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1201661999 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1201661939) 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, 62834 + ... + 79695.

It is an arithmetic number, because the mean of its divisors is an integer number (300453240).

Almost surely, 2^1201661999 is an apocalyptic number.

1201661999 is a deficient number, since it is larger than the sum of its proper divisors (150961).

1201661999 is an equidigital number, since it uses as much as digits as its factorization.

1201661999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150960.

The product of its (nonzero) digits is 52488, while the sum is 44.

The square root of 1201661999 is about 34664.9967402277. The cubic root of 1201661999 is about 1063.1489366103.

The spelling of 1201661999 in words is "one billion, two hundred one million, six hundred sixty-one thousand, nine hundred ninety-nine".