521113781 has 2 divisors, whose sum is σ = 521113782. Its totient is φ = 521113780.

The previous prime is 521113717. The next prime is 521113787. The reversal of 521113781 is 187311125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 369946756 + 151167025 = 19234^2 + 12295^2 .

It is a cyclic number.

It is not a de Polignac number, because 521113781 - 2⁶ = 521113717 is a prime.

It is a super-2 number, since 2×521113781² = 543119145496231922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521113787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260556890 + 260556891.

It is an arithmetic number, because the mean of its divisors is an integer number (260556891).

Almost surely, 2^521113781 is an apocalyptic number.

It is an amenable number.

521113781 is a deficient number, since it is larger than the sum of its proper divisors (1).

521113781 is an equidigital number, since it uses as much as digits as its factorization.

521113781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 29.

The square root of 521113781 is about 22827.9167030196. The cubic root of 521113781 is about 804.7188715235.

The spelling of 521113781 in words is "five hundred twenty-one million, one hundred thirteen thousand, seven hundred eighty-one".