521401021 has 8 divisors (see below), whose sum is σ = 549190400. Its totient is φ = 493646400.

The previous prime is 521401009. The next prime is 521401031. The reversal of 521401021 is 120104125.

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 521401021 - 2²³ = 513012413 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 521400986 and 521401004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521401031) 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 7 ways as a sum of consecutive naturals, for example, 25621 + ... + 41221.

It is an arithmetic number, because the mean of its divisors is an integer number (68648800).

Almost surely, 2^521401021 is an apocalyptic number.

It is an amenable number.

521401021 is a deficient number, since it is larger than the sum of its proper divisors (27789379).

521401021 is a wasteful number, since it uses less digits than its factorization.

521401021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17379.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 521401021 is about 22834.2072557818. The cubic root of 521401021 is about 804.8666991191.

Adding to 521401021 its reverse (120104125), we get a palindrome (641505146).

The spelling of 521401021 in words is "five hundred twenty-one million, four hundred one thousand, twenty-one".