420810661 has 2 divisors, whose sum is σ = 420810662. Its totient is φ = 420810660.

The previous prime is 420810653. The next prime is 420810671. The reversal of 420810661 is 166018024.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 415548225 + 5262436 = 20385^2 + 2294^2 .

It is a cyclic number.

It is not a de Polignac number, because 420810661 - 2³ = 420810653 is a prime.

It is a super-2 number, since 2×420810661² = 354163224822513842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (420810631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210405330 + 210405331.

It is an arithmetic number, because the mean of its divisors is an integer number (210405331).

Almost surely, 2^420810661 is an apocalyptic number.

It is an amenable number.

420810661 is a deficient number, since it is larger than the sum of its proper divisors (1).

420810661 is an equidigital number, since it uses as much as digits as its factorization.

420810661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 420810661 is about 20513.6701006914. The cubic root of 420810661 is about 749.3687494386.

Adding to 420810661 its reverse (166018024), we get a palindrome (586828685).

The spelling of 420810661 in words is "four hundred twenty million, eight hundred ten thousand, six hundred sixty-one".