125999021 has 2 divisors, whose sum is σ = 125999022. Its totient is φ = 125999020.

The previous prime is 125999009. The next prime is 125999059. The reversal of 125999021 is 120999521.

It is an a-pointer prime, because the next prime (125999059) can be obtained adding 125999021 to its sum of digits (38).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 87422500 + 38576521 = 9350^2 + 6211^2 .

It is a cyclic number.

It is not a de Polignac number, because 125999021 - 2¹⁰ = 125997997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (125999521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62999510 + 62999511.

It is an arithmetic number, because the mean of its divisors is an integer number (62999511).

Almost surely, 2^125999021 is an apocalyptic number.

It is an amenable number.

125999021 is a deficient number, since it is larger than the sum of its proper divisors (1).

125999021 is an equidigital number, since it uses as much as digits as its factorization.

125999021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14580, while the sum is 38.

The square root of 125999021 is about 11224.9285521111. The cubic root of 125999021 is about 501.3284950755.

The spelling of 125999021 in words is "one hundred twenty-five million, nine hundred ninety-nine thousand, twenty-one".