1375552721 has 2 divisors, whose sum is σ = 1375552722. Its totient is φ = 1375552720.

The previous prime is 1375552691. The next prime is 1375552753. The reversal of 1375552721 is 1272555731.

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., 1351591696 + 23961025 = 36764^2 + 4895^2 .

It is a cyclic number.

It is not a de Polignac number, because 1375552721 - 2³⁰ = 301810897 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1375552021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 687776360 + 687776361.

It is an arithmetic number, because the mean of its divisors is an integer number (687776361).

Almost surely, 2^1375552721 is an apocalyptic number.

It is an amenable number.

1375552721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1375552721 is an equidigital number, since it uses as much as digits as its factorization.

1375552721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 73500, while the sum is 38.

The square root of 1375552721 is about 37088.4445750964. Note that the first 3 decimals coincide. The cubic root of 1375552721 is about 1112.1390241728.

The spelling of 1375552721 in words is "one billion, three hundred seventy-five million, five hundred fifty-two thousand, seven hundred twenty-one".