420135666581 has 2 divisors, whose sum is σ = 420135666582. Its totient is φ = 420135666580.

The previous prime is 420135666569. The next prime is 420135666647. The reversal of 420135666581 is 185666531024.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 274192565956 + 145943100625 = 523634^2 + 382025^2 .

It is a cyclic number.

It is not a de Polignac number, because 420135666581 - 2¹⁰ = 420135665557 is a prime.

It is a super-2 number, since 2×420135666581² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (420135666281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210067833290 + 210067833291.

It is an arithmetic number, because the mean of its divisors is an integer number (210067833291).

Almost surely, 2^420135666581 is an apocalyptic number.

It is an amenable number.

420135666581 is a deficient number, since it is larger than the sum of its proper divisors (1).

420135666581 is an equidigital number, since it uses as much as digits as its factorization.

420135666581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1036800, while the sum is 47.

The spelling of 420135666581 in words is "four hundred twenty billion, one hundred thirty-five million, six hundred sixty-six thousand, five hundred eighty-one".