721369987 has 4 divisors (see below), whose sum is σ = 776860000. Its totient is φ = 665879976.

The previous prime is 721369981. The next prime is 721369991. The reversal of 721369987 is 789963127.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 721369987 - 2²⁷ = 587152259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721369981) 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 in 3 ways as a sum of consecutive naturals, for example, 27744987 + ... + 27745012.

It is an arithmetic number, because the mean of its divisors is an integer number (194215000).

Almost surely, 2^721369987 is an apocalyptic number.

721369987 is a deficient number, since it is larger than the sum of its proper divisors (55490013).

721369987 is a wasteful number, since it uses less digits than its factorization.

721369987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55490012.

The product of its digits is 1143072, while the sum is 52.

The square root of 721369987 is about 26858.3317985313. The cubic root of 721369987 is about 896.8490582354.

The spelling of 721369987 in words is "seven hundred twenty-one million, three hundred sixty-nine thousand, nine hundred eighty-seven".