1661278297 has 8 divisors (see below), whose sum is σ = 1942757696. Its totient is φ = 1390837392.

The previous prime is 1661278277. The next prime is 1661278337. The reversal of 1661278297 is 7928721661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1661278297 - 2¹¹ = 1661276249 is a prime.

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 1661278297.

It is not an unprimeable number, because it can be changed into a prime (1661278277) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2759298 + ... + 2759899.

It is an arithmetic number, because the mean of its divisors is an integer number (242844712).

Almost surely, 2^1661278297 is an apocalyptic number.

It is an amenable number.

1661278297 is a deficient number, since it is larger than the sum of its proper divisors (281479399).

1661278297 is an equidigital number, since it uses as much as digits as its factorization.

1661278297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5519247.

The product of its digits is 508032, while the sum is 49.

The square root of 1661278297 is about 40758.7818390099. The cubic root of 1661278297 is about 1184.3519983159.

The spelling of 1661278297 in words is "one billion, six hundred sixty-one million, two hundred seventy-eight thousand, two hundred ninety-seven".