1378995721 has 2 divisors, whose sum is σ = 1378995722. Its totient is φ = 1378995720.

The previous prime is 1378995703. The next prime is 1378995799. The reversal of 1378995721 is 1275998731.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1023296121 + 355699600 = 31989^2 + 18860^2 .

It is a cyclic number.

It is not a de Polignac number, because 1378995721 - 2⁵ = 1378995689 is a prime.

It is not a weakly prime, because it can be changed into another prime (1378995221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 689497860 + 689497861.

It is an arithmetic number, because the mean of its divisors is an integer number (689497861).

Almost surely, 2^1378995721 is an apocalyptic number.

It is an amenable number.

1378995721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1378995721 is an equidigital number, since it uses as much as digits as its factorization.

1378995721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 952560, while the sum is 52.

The square root of 1378995721 is about 37134.8316409271. The cubic root of 1378995721 is about 1113.0661434569.

The spelling of 1378995721 in words is "one billion, three hundred seventy-eight million, nine hundred ninety-five thousand, seven hundred twenty-one".