523021981 has 2 divisors, whose sum is σ = 523021982. Its totient is φ = 523021980.

The previous prime is 523021979. The next prime is 523022039. The reversal of 523021981 is 189120325.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 356869881 + 166152100 = 18891^2 + 12890^2 .

It is a cyclic number.

It is not a de Polignac number, because 523021981 - 2¹ = 523021979 is a prime.

It is a super-2 number, since 2×523021981² = 547103985218328722, which contains 22 as substring.

Together with 523021979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (523021921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 261510990 + 261510991.

It is an arithmetic number, because the mean of its divisors is an integer number (261510991).

Almost surely, 2^523021981 is an apocalyptic number.

It is an amenable number.

523021981 is a deficient number, since it is larger than the sum of its proper divisors (1).

523021981 is an equidigital number, since it uses as much as digits as its factorization.

523021981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 523021981 is about 22869.6738280195. The cubic root of 523021981 is about 805.6999074727.

The spelling of 523021981 in words is "five hundred twenty-three million, twenty-one thousand, nine hundred eighty-one".