521821740 has 96 divisors (see below), whose sum is σ = 1598446080. Its totient is φ = 126144000.

The previous prime is 521821709. The next prime is 521821753. The reversal of 521821740 is 47128125.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 521821698 and 521821707.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 288840 + ... + 290640.

It is an arithmetic number, because the mean of its divisors is an integer number (16650480).

Almost surely, 2^521821740 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521821740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (799223040).

521821740 is an abundant number, since it is smaller than the sum of its proper divisors (1076624340).

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

521821740 is a wasteful number, since it uses less digits than its factorization.

521821740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2263 (or 2261 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 30.

The square root of 521821740 is about 22843.4178703626. The cubic root of 521821740 is about 805.0831234973.

Adding to 521821740 its reverse (47128125), we get a palindrome (568949865).

The spelling of 521821740 in words is "five hundred twenty-one million, eight hundred twenty-one thousand, seven hundred forty".