661125013 has 4 divisors (see below), whose sum is σ = 661923340. Its totient is φ = 660326688.

The previous prime is 661125001. The next prime is 661125037. The reversal of 661125013 is 310521166.

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

It can be written as a sum of positive squares in 2 ways, for example, as 344213809 + 316911204 = 18553^2 + 17802^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661125013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661125613) 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, 397920 + ... + 399577.

It is an arithmetic number, because the mean of its divisors is an integer number (165480835).

Almost surely, 2^661125013 is an apocalyptic number.

It is an amenable number.

661125013 is a deficient number, since it is larger than the sum of its proper divisors (798327).

661125013 is an equidigital number, since it uses as much as digits as its factorization.

661125013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798326.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 661125013 is about 25712.3513704990. The cubic root of 661125013 is about 871.1531865004.

Adding to 661125013 its reverse (310521166), we get a palindrome (971646179).

The spelling of 661125013 in words is "six hundred sixty-one million, one hundred twenty-five thousand, thirteen".