1215125661 has 8 divisors (see below), whose sum is σ = 1642361920. Its totient is φ = 798986592.

The previous prime is 1215125617. The next prime is 1215125669. The reversal of 1215125661 is 1665215121.

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

It is not a de Polignac number, because 1215125661 - 2¹⁴ = 1215109277 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 (1215125669) 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, 2774041 + ... + 2774478.

It is an arithmetic number, because the mean of its divisors is an integer number (205295240).

Almost surely, 2^1215125661 is an apocalyptic number.

It is an amenable number.

1215125661 is a deficient number, since it is larger than the sum of its proper divisors (427236259).

1215125661 is an equidigital number, since it uses as much as digits as its factorization.

1215125661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5548595.

The product of its digits is 3600, while the sum is 30.

The square root of 1215125661 is about 34858.6525987451. The cubic root of 1215125661 is about 1067.1047771381.

The spelling of 1215125661 in words is "one billion, two hundred fifteen million, one hundred twenty-five thousand, six hundred sixty-one".