1661119993 has 4 divisors (see below), whose sum is σ = 1788898468. Its totient is φ = 1533341520.

The previous prime is 1661119991. The next prime is 1661120009. The reversal of 1661119993 is 3999111661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3999111661 = 53 ⋅75454937.

It can be written as a sum of positive squares in 2 ways, for example, as 401721849 + 1259398144 = 20043^2 + 35488^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661119993 - 2¹ = 1661119991 is a prime.

It is a super-2 number, since 2×1661119993² = 5518639262288640098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661119991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63889218 + ... + 63889243.

It is an arithmetic number, because the mean of its divisors is an integer number (447224617).

Almost surely, 2^1661119993 is an apocalyptic number.

1661119993 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

1661119993 is a deficient number, since it is larger than the sum of its proper divisors (127778475).

1661119993 is a wasteful number, since it uses less digits than its factorization.

1661119993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127778474.

The product of its digits is 78732, while the sum is 46.

The square root of 1661119993 is about 40756.8398308799. The cubic root of 1661119993 is about 1184.3143779657.

The spelling of 1661119993 in words is "one billion, six hundred sixty-one million, one hundred nineteen thousand, nine hundred ninety-three".