8429259721 has 3 divisors (see below), whose sum is σ = 8429351533. Its totient is φ = 8429167910.

The previous prime is 8429259677. The next prime is 8429259757. The reversal of 8429259721 is 1279529248.

It is a happy number.

The square root of 8429259721 is 91811.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 8429259721 - 2⁷ = 8429259593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8429259221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 45906 + ... + 137716.

Almost surely, 2^8429259721 is an apocalyptic number.

8429259721 is the 91811-st square number.

8429259721 is the 45906-th centered octagonal number.

It is an amenable number.

8429259721 is a deficient number, since it is larger than the sum of its proper divisors (91812).

8429259721 is an frugal number, since it uses more digits than its factorization.

8429259721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183622 (or 91811 counting only the distinct ones).

The product of its digits is 725760, while the sum is 49.

The cubic root of 8429259721 is about 2035.1502541050.

Multiplying 8429259721 by its sum of digits (49), we get a square (413033726329 = 642677²).

The spelling of 8429259721 in words is "eight billion, four hundred twenty-nine million, two hundred fifty-nine thousand, seven hundred twenty-one".