721533539 has 4 divisors (see below), whose sum is σ = 739131960. Its totient is φ = 703935120.

The previous prime is 721533523. The next prime is 721533563. The reversal of 721533539 is 935335127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 935335127 = 2089 ⋅447743.

It is a cyclic number.

It is not a de Polignac number, because 721533539 - 2⁴ = 721533523 is a prime.

It is a super-2 number, since 2×721533539² = 1041221295803729042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721533509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8799149 + ... + 8799230.

It is an arithmetic number, because the mean of its divisors is an integer number (184782990).

Almost surely, 2^721533539 is an apocalyptic number.

721533539 is a deficient number, since it is larger than the sum of its proper divisors (17598421).

721533539 is a wasteful number, since it uses less digits than its factorization.

721533539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17598420.

The product of its digits is 85050, while the sum is 38.

The square root of 721533539 is about 26861.3763422502. The cubic root of 721533539 is about 896.9168322283.

The spelling of 721533539 in words is "seven hundred twenty-one million, five hundred thirty-three thousand, five hundred thirty-nine".