1297197721 has 4 divisors (see below), whose sum is σ = 1297977552. Its totient is φ = 1296417892.

The previous prime is 1297197709. The next prime is 1297197731. The reversal of 1297197721 is 1277917921.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1297197721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1297197731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 387415 + ... + 390748.

It is an arithmetic number, because the mean of its divisors is an integer number (324494388).

Almost surely, 2^1297197721 is an apocalyptic number.

It is an amenable number.

1297197721 is a deficient number, since it is larger than the sum of its proper divisors (779831).

1297197721 is an equidigital number, since it uses as much as digits as its factorization.

1297197721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 779830.

The product of its digits is 111132, while the sum is 46.

The square root of 1297197721 is about 36016.6311722793. The cubic root of 1297197721 is about 1090.6081170240.

The spelling of 1297197721 in words is "one billion, two hundred ninety-seven million, one hundred ninety-seven thousand, seven hundred twenty-one".