521978987 has 2 divisors, whose sum is σ = 521978988. Its totient is φ = 521978986.

The previous prime is 521978983. The next prime is 521979049. The reversal of 521978987 is 789879125.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 521978987 - 2² = 521978983 is a prime.

It is a super-3 number, since 3×521978987³ (a number of 27 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (521978983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260989493 + 260989494.

It is an arithmetic number, because the mean of its divisors is an integer number (260989494).

Almost surely, 2^521978987 is an apocalyptic number.

521978987 is a deficient number, since it is larger than the sum of its proper divisors (1).

521978987 is an equidigital number, since it uses as much as digits as its factorization.

521978987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2540160, while the sum is 56.

The square root of 521978987 is about 22846.8594559515. The cubic root of 521978987 is about 805.1639839278.

The spelling of 521978987 in words is "five hundred twenty-one million, nine hundred seventy-eight thousand, nine hundred eighty-seven".