721721477629 has 4 divisors (see below), whose sum is σ = 739324440540. Its totient is φ = 704118514720.

The previous prime is 721721477579. The next prime is 721721477657. The reversal of 721721477629 is 926774127127.

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

It can be written as a sum of positive squares in 2 ways, for example, as 157573272025 + 564148205604 = 396955^2 + 751098^2 .

It is a cyclic number.

It is not a de Polignac number, because 721721477629 - 2¹¹ = 721721475581 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721721477629.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721721471629) 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, 8801481394 + ... + 8801481475.

It is an arithmetic number, because the mean of its divisors is an integer number (184831110135).

Almost surely, 2^721721477629 is an apocalyptic number.

It is an amenable number.

721721477629 is a deficient number, since it is larger than the sum of its proper divisors (17602962911).

721721477629 is a wasteful number, since it uses less digits than its factorization.

721721477629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17602962910.

The product of its digits is 4148928, while the sum is 55.

The spelling of 721721477629 in words is "seven hundred twenty-one billion, seven hundred twenty-one million, four hundred seventy-seven thousand, six hundred twenty-nine".