1245721 has 2 divisors, whose sum is σ = 1245722. Its totient is φ = 1245720.

The previous prime is 1245719. The next prime is 1245763. The reversal of 1245721 is 1275421.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1210000 + 35721 = 1100^2 + 189^2 .

It is a cyclic number.

It is not a de Polignac number, because 1245721 - 2¹ = 1245719 is a prime.

Together with 1245719, it forms a pair of twin primes.

1245721 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1245692 and 1245701.

It is not a weakly prime, because it can be changed into another prime (1245701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 622860 + 622861.

It is an arithmetic number, because the mean of its divisors is an integer number (622861).

2^1245721 is an apocalyptic number.

It is an amenable number.

1245721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1245721 is an equidigital number, since it uses as much as digits as its factorization.

1245721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 560, while the sum is 22.

The square root of 1245721 is about 1116.1187212837. The cubic root of 1245721 is about 107.5986762965.

The spelling of 1245721 in words is "one million, two hundred forty-five thousand, seven hundred twenty-one".