1396543721 has 2 divisors, whose sum is σ = 1396543722. Its totient is φ = 1396543720.

The previous prime is 1396543697. The next prime is 1396543781. The reversal of 1396543721 is 1273456931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1281282025 + 115261696 = 35795^2 + 10736^2 .

It is a cyclic number.

It is not a de Polignac number, because 1396543721 - 2⁶ = 1396543657 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 (1396543781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 698271860 + 698271861.

It is an arithmetic number, because the mean of its divisors is an integer number (698271861).

Almost surely, 2^1396543721 is an apocalyptic number.

It is an amenable number.

1396543721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1396543721 is an equidigital number, since it uses as much as digits as its factorization.

1396543721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 41.

The square root of 1396543721 is about 37370.3588556492. The cubic root of 1396543721 is about 1117.7675879614.

The spelling of 1396543721 in words is "one billion, three hundred ninety-six million, five hundred forty-three thousand, seven hundred twenty-one".