1297721 has 8 divisors (see below), whose sum is σ = 1363080. Its totient is φ = 1233792.

The previous prime is 1297693. The next prime is 1297727. The reversal of 1297721 is 1277921.

It can be written as a sum of positive squares in 4 ways, for example, as 7225 + 1290496 = 85^2 + 1136^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1297721 - 2⁶ = 1297657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1297727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1811 + ... + 2423.

It is an arithmetic number, because the mean of its divisors is an integer number (170385).

2^1297721 is an apocalyptic number.

It is an amenable number.

1297721 is a deficient number, since it is larger than the sum of its proper divisors (65359).

1297721 is an equidigital number, since it uses as much as digits as its factorization.

1297721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 715.

The product of its digits is 1764, while the sum is 29.

The square root of 1297721 is about 1139.1755790922. The cubic root of 1297721 is about 109.0754744788.

The spelling of 1297721 in words is "one million, two hundred ninety-seven thousand, seven hundred twenty-one".