521401720 has 64 divisors (see below), whose sum is σ = 1399057920. Its totient is φ = 170991744.

The previous prime is 521401711. The next prime is 521401721. The reversal of 521401720 is 27104125.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 521401691 and 521401700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521401721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34042 + ... + 46921.

It is an arithmetic number, because the mean of its divisors is an integer number (21860280).

Almost surely, 2^521401720 is an apocalyptic number.

It is an amenable number.

521401720 is an abundant number, since it is smaller than the sum of its proper divisors (877656200).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521401720 is a wasteful number, since it uses less digits than its factorization.

521401720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81004 (or 81000 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 521401720 is about 22834.2225617602. Note that the first 3 decimals coincide. The cubic root of 521401720 is about 804.8670587921.

Adding to 521401720 its reverse (27104125), we get a palindrome (548505845).

The spelling of 521401720 in words is "five hundred twenty-one million, four hundred one thousand, seven hundred twenty".