721007647 has 2 divisors, whose sum is σ = 721007648. Its totient is φ = 721007646.

The previous prime is 721007603. The next prime is 721007659. The reversal of 721007647 is 746700127.

It is a strong prime.

It is an emirp because it is prime and its reverse (746700127) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721007647 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721007047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360503823 + 360503824.

It is an arithmetic number, because the mean of its divisors is an integer number (360503824).

Almost surely, 2^721007647 is an apocalyptic number.

721007647 is a deficient number, since it is larger than the sum of its proper divisors (1).

721007647 is an equidigital number, since it uses as much as digits as its factorization.

721007647 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16464, while the sum is 34.

The square root of 721007647 is about 26851.5855583986. The cubic root of 721007647 is about 896.6988723770.

The spelling of 721007647 in words is "seven hundred twenty-one million, seven thousand, six hundred forty-seven".