1661278325 has 24 divisors (see below), whose sum is σ = 2355825408. Its totient is φ = 1138409280.

The previous prime is 1661278277. The next prime is 1661278337. The reversal of 1661278325 is 5238721661.

It is not a de Polignac number, because 1661278325 - 2⁶ = 1661278261 is a prime.

It is a super-2 number, since 2×1661278325² = 5519691346229611250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 443159 + ... + 446891.

It is an arithmetic number, because the mean of its divisors is an integer number (98159392).

Almost surely, 2^1661278325 is an apocalyptic number.

It is an amenable number.

1661278325 is a deficient number, since it is larger than the sum of its proper divisors (694547083).

1661278325 is a wasteful number, since it uses less digits than its factorization.

1661278325 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6293 (or 6288 counting only the distinct ones).

The product of its digits is 120960, while the sum is 41.

The square root of 1661278325 is about 40758.7821824941. The cubic root of 1661278325 is about 1184.3520049698.

Adding to 1661278325 its reverse (5238721661), we get a palindrome (6899999986).

The spelling of 1661278325 in words is "one billion, six hundred sixty-one million, two hundred seventy-eight thousand, three hundred twenty-five".