521870387 has 2 divisors, whose sum is σ = 521870388. Its totient is φ = 521870386.

The previous prime is 521870347. The next prime is 521870389. The reversal of 521870387 is 783078125.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 521870387 - 2²² = 517676083 is a prime.

Together with 521870389, it forms a pair of twin primes.

It is a Chen prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (521870389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260935193 + 260935194.

It is an arithmetic number, because the mean of its divisors is an integer number (260935194).

Almost surely, 2^521870387 is an apocalyptic number.

521870387 is a deficient number, since it is larger than the sum of its proper divisors (1).

521870387 is an equidigital number, since it uses as much as digits as its factorization.

521870387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 94080, while the sum is 41.

The square root of 521870387 is about 22844.4826380463. The cubic root of 521870387 is about 805.1081407645.

The spelling of 521870387 in words is "five hundred twenty-one million, eight hundred seventy thousand, three hundred eighty-seven".