125121721787 has 4 divisors (see below), whose sum is σ = 127172897616. Its totient is φ = 123070545960.

The previous prime is 125121721663. The next prime is 125121721853. The reversal of 125121721787 is 787127121521.

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

It is a cyclic number.

It is not a de Polignac number, because 125121721787 - 2⁸ = 125121721531 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (125121721187) 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, 1025587823 + ... + 1025587944.

It is an arithmetic number, because the mean of its divisors is an integer number (31793224404).

Almost surely, 2^125121721787 is an apocalyptic number.

125121721787 is a deficient number, since it is larger than the sum of its proper divisors (2051175829).

125121721787 is an equidigital number, since it uses as much as digits as its factorization.

125121721787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2051175828.

The product of its digits is 109760, while the sum is 44.

The spelling of 125121721787 in words is "one hundred twenty-five billion, one hundred twenty-one million, seven hundred twenty-one thousand, seven hundred eighty-seven".