125866735521 has 4 divisors (see below), whose sum is σ = 167822314032. Its totient is φ = 83911157012.

The previous prime is 125866735481. The next prime is 125866735541. The reversal of 125866735521 is 125537668521.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 125537668521 = 3 ⋅41845889507.

It is a cyclic number.

It is not a de Polignac number, because 125866735521 - 2⁹ = 125866735009 is a prime.

It is a super-2 number, since 2×125866735521² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (125866735541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20977789251 + ... + 20977789256.

It is an arithmetic number, because the mean of its divisors is an integer number (41955578508).

Almost surely, 2^125866735521 is an apocalyptic number.

It is an amenable number.

125866735521 is a deficient number, since it is larger than the sum of its proper divisors (41955578511).

125866735521 is an equidigital number, since it uses as much as digits as its factorization.

125866735521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41955578510.

The product of its digits is 3024000, while the sum is 51.

The spelling of 125866735521 in words is "one hundred twenty-five billion, eight hundred sixty-six million, seven hundred thirty-five thousand, five hundred twenty-one".