1661204747 has 4 divisors (see below), whose sum is σ = 1662160656. Its totient is φ = 1660248840.

The previous prime is 1661204731. The next prime is 1661204771. The reversal of 1661204747 is 7474021661.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1661204747 - 2⁴ = 1661204731 is a prime.

It is a super-2 number, since 2×1661204747² = 5519202422910668018, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661204747.

It is not an unprimeable number, because it can be changed into a prime (1661204047) 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, 475343 + ... + 478824.

It is an arithmetic number, because the mean of its divisors is an integer number (415540164).

Almost surely, 2^1661204747 is an apocalyptic number.

1661204747 is a deficient number, since it is larger than the sum of its proper divisors (955909).

1661204747 is an equidigital number, since it uses as much as digits as its factorization.

1661204747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 955908.

The product of its (nonzero) digits is 56448, while the sum is 38.

The square root of 1661204747 is about 40757.8795694771. The cubic root of 1661204747 is about 1184.3345197323.

The spelling of 1661204747 in words is "one billion, six hundred sixty-one million, two hundred four thousand, seven hundred forty-seven".