721387 has 2 divisors, whose sum is σ = 721388. Its totient is φ = 721386.

The previous prime is 721381. The next prime is 721397. The reversal of 721387 is 783127.

It is a happy number.

721387 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 721387 - 2³ = 721379 is a prime.

It is not a weakly prime, because it can be changed into another prime (721381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360693 + 360694.

It is an arithmetic number, because the mean of its divisors is an integer number (360694).

2⁷²¹³⁸⁷ is an apocalyptic number.

721387 is a deficient number, since it is larger than the sum of its proper divisors (1).

721387 is an equidigital number, since it uses as much as digits as its factorization.

721387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2352, while the sum is 28.

The square root of 721387 is about 849.3450417822. The cubic root of 721387 is about 89.6856108697.

The spelling of 721387 in words is "seven hundred twenty-one thousand, three hundred eighty-seven".