721721258 has 4 divisors (see below), whose sum is σ = 1082581890. Its totient is φ = 360860628.

The previous prime is 721721257. The next prime is 721721279. The reversal of 721721258 is 852127127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 852127127 = 919 ⋅927233.

It can be written as a sum of positive squares in only one way, i.e., 721620769 + 100489 = 26863^2 + 317^2 .

It is not an unprimeable number, because it can be changed into a prime (721721257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180430313 + ... + 180430316.

Almost surely, 2^721721258 is an apocalyptic number.

721721258 is a deficient number, since it is larger than the sum of its proper divisors (360860632).

721721258 is a wasteful number, since it uses less digits than its factorization.

721721258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360860631.

The product of its digits is 15680, while the sum is 35.

The square root of 721721258 is about 26864.8703328343. The cubic root of 721721258 is about 896.9946081147.

The spelling of 721721258 in words is "seven hundred twenty-one million, seven hundred twenty-one thousand, two hundred fifty-eight".