1297999621 has 4 divisors (see below), whose sum is σ = 1299928972. Its totient is φ = 1296070272.

The previous prime is 1297999601. The next prime is 1297999631. The reversal of 1297999621 is 1269997921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1269997921 = 1051 ⋅1208371.

It can be written as a sum of positive squares in 2 ways, for example, as 774230625 + 523768996 = 27825^2 + 22886^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1297999621 is a prime.

It is a super-2 number, since 2×1297999621² = 3369606032232287282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1297999601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 963666 + ... + 965011.

It is an arithmetic number, because the mean of its divisors is an integer number (324982243).

Almost surely, 2^1297999621 is an apocalyptic number.

It is an amenable number.

1297999621 is a deficient number, since it is larger than the sum of its proper divisors (1929351).

1297999621 is an equidigital number, since it uses as much as digits as its factorization.

1297999621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1929350.

The product of its digits is 1102248, while the sum is 55.

The square root of 1297999621 is about 36027.7618094713. The cubic root of 1297999621 is about 1090.8328009678.

The spelling of 1297999621 in words is "one billion, two hundred ninety-seven million, nine hundred ninety-nine thousand, six hundred twenty-one".