721423457 has 4 divisors (see below), whose sum is σ = 722266116. Its totient is φ = 720580800.

The previous prime is 721423453. The next prime is 721423463. The reversal of 721423457 is 754324127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 754324127 = 821 ⋅918787.

It can be written as a sum of positive squares in 2 ways, for example, as 589081441 + 132342016 = 24271^2 + 11504^2 .

It is a cyclic number.

It is not a de Polignac number, because 721423457 - 2² = 721423453 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721423453) 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, 420044 + ... + 421757.

It is an arithmetic number, because the mean of its divisors is an integer number (180566529).

Almost surely, 2^721423457 is an apocalyptic number.

It is an amenable number.

721423457 is a deficient number, since it is larger than the sum of its proper divisors (842659).

721423457 is an equidigital number, since it uses as much as digits as its factorization.

721423457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 842658.

The product of its digits is 47040, while the sum is 35.

The square root of 721423457 is about 26859.3271881483. The cubic root of 721423457 is about 896.8712166910.

The spelling of 721423457 in words is "seven hundred twenty-one million, four hundred twenty-three thousand, four hundred fifty-seven".