125721206981 has 2 divisors, whose sum is σ = 125721206982. Its totient is φ = 125721206980.

The previous prime is 125721206953. The next prime is 125721207019. The reversal of 125721206981 is 189602127521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 96602856100 + 29118350881 = 310810^2 + 170641^2 .

It is a cyclic number.

It is not a de Polignac number, because 125721206981 - 2²² = 125717012677 is a prime.

It is a super-2 number, since 2×125721206981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (125721206081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62860603490 + 62860603491.

It is an arithmetic number, because the mean of its divisors is an integer number (62860603491).

Almost surely, 2^125721206981 is an apocalyptic number.

It is an amenable number.

125721206981 is a deficient number, since it is larger than the sum of its proper divisors (1).

125721206981 is an equidigital number, since it uses as much as digits as its factorization.

125721206981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120960, while the sum is 44.

The spelling of 125721206981 in words is "one hundred twenty-five billion, seven hundred twenty-one million, two hundred six thousand, nine hundred eighty-one".