721340987 has 2 divisors, whose sum is σ = 721340988. Its totient is φ = 721340986.

The previous prime is 721340981. The next prime is 721341001. The reversal of 721340987 is 789043127.

It is a weak prime.

It is an emirp because it is prime and its reverse (789043127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721340987 - 2¹⁰ = 721339963 is a prime.

It is a super-2 number, since 2×721340987² = 1040665639052268338, which contains 22 as substring.

It is a Chen prime.

It is equal to p_37299902 and since 721340987 and 37299902 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (721340981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360670493 + 360670494.

It is an arithmetic number, because the mean of its divisors is an integer number (360670494).

Almost surely, 2^721340987 is an apocalyptic number.

721340987 is a deficient number, since it is larger than the sum of its proper divisors (1).

721340987 is an equidigital number, since it uses as much as digits as its factorization.

721340987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84672, while the sum is 41.

The square root of 721340987 is about 26857.7919233879. The cubic root of 721340987 is about 896.8370399130.

The spelling of 721340987 in words is "seven hundred twenty-one million, three hundred forty thousand, nine hundred eighty-seven".