521899821 has 16 divisors (see below), whose sum is σ = 774381120. Its totient is φ = 347394960.

The previous prime is 521899801. The next prime is 521899841. The reversal of 521899821 is 128998125.

It is an interprime number because it is at equal distance from previous prime (521899801) and next prime (521899841).

It is not a de Polignac number, because 521899821 - 2¹⁷ = 521768749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521899801) 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, 3226 + ... + 32468.

It is an arithmetic number, because the mean of its divisors is an integer number (48398820).

Almost surely, 2^521899821 is an apocalyptic number.

It is an amenable number.

521899821 is a deficient number, since it is larger than the sum of its proper divisors (252481299).

521899821 is a wasteful number, since it uses less digits than its factorization.

521899821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29913 (or 29907 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 521899821 is about 22845.1268545395. The cubic root of 521899821 is about 805.1232767753.

The spelling of 521899821 in words is "five hundred twenty-one million, eight hundred ninety-nine thousand, eight hundred twenty-one".