521721247 has 8 divisors (see below), whose sum is σ = 558489600. Its totient is φ = 485883864.

The previous prime is 521721191. The next prime is 521721271. The reversal of 521721247 is 742127125.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 521721247 - 2⁷ = 521721119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521721047) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 231583 + ... + 233824.

It is an arithmetic number, because the mean of its divisors is an integer number (69811200).

Almost surely, 2^521721247 is an apocalyptic number.

521721247 is a deficient number, since it is larger than the sum of its proper divisors (36768353).

521721247 is a wasteful number, since it uses less digits than its factorization.

521721247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 465485.

The product of its digits is 7840, while the sum is 31.

The square root of 521721247 is about 22841.2181592839. The cubic root of 521721247 is about 805.0314389172.

The spelling of 521721247 in words is "five hundred twenty-one million, seven hundred twenty-one thousand, two hundred forty-seven".