125121721 has 2 divisors, whose sum is σ = 125121722. Its totient is φ = 125121720.

The previous prime is 125121691. The next prime is 125121739. The reversal of 125121721 is 127121521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 124099600 + 1022121 = 11140^2 + 1011^2 .

It is an emirp because it is prime and its reverse (127121521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 125121721 - 2¹³ = 125113529 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 125121692 and 125121701.

It is not a weakly prime, because it can be changed into another prime (125121761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62560860 + 62560861.

It is an arithmetic number, because the mean of its divisors is an integer number (62560861).

Almost surely, 2^125121721 is an apocalyptic number.

It is an amenable number.

125121721 is a deficient number, since it is larger than the sum of its proper divisors (1).

125121721 is an equidigital number, since it uses as much as digits as its factorization.

125121721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 280, while the sum is 22.

The square root of 125121721 is about 11185.7820915661. The cubic root of 125121721 is about 500.1622420160.

The spelling of 125121721 in words is "one hundred twenty-five million, one hundred twenty-one thousand, seven hundred twenty-one".