721541969 has 8 divisors (see below), whose sum is σ = 730252488. Its totient is φ = 712857600.

The previous prime is 721541939. The next prime is 721541971. The reversal of 721541969 is 969145127.

It can be written as a sum of positive squares in 4 ways, for example, as 77651344 + 643890625 = 8812^2 + 25375^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721541969 - 2¹⁶ = 721476433 is a prime.

It is a super-2 number, since 2×721541969² = 1041245626056793922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721541939) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52109 + ... + 64485.

It is an arithmetic number, because the mean of its divisors is an integer number (91281561).

Almost surely, 2^721541969 is an apocalyptic number.

It is an amenable number.

721541969 is a deficient number, since it is larger than the sum of its proper divisors (8710519).

721541969 is a wasteful number, since it uses less digits than its factorization.

721541969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13075.

The product of its digits is 136080, while the sum is 44.

The square root of 721541969 is about 26861.5332585465. The cubic root of 721541969 is about 896.9203252420.

The spelling of 721541969 in words is "seven hundred twenty-one million, five hundred forty-one thousand, nine hundred sixty-nine".