420636521 has 2 divisors, whose sum is σ = 420636522. Its totient is φ = 420636520.

The previous prime is 420636499. The next prime is 420636529. The reversal of 420636521 is 125636024.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 276756496 + 143880025 = 16636^2 + 11995^2 .

It is a cyclic number.

It is not a de Polignac number, because 420636521 - 2¹⁸ = 420374377 is a prime.

It is not a weakly prime, because it can be changed into another prime (420636529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210318260 + 210318261.

It is an arithmetic number, because the mean of its divisors is an integer number (210318261).

Almost surely, 2^420636521 is an apocalyptic number.

It is an amenable number.

420636521 is a deficient number, since it is larger than the sum of its proper divisors (1).

420636521 is an equidigital number, since it uses as much as digits as its factorization.

420636521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 420636521 is about 20509.4251747824. The cubic root of 420636521 is about 749.2653671729.

It can be divided in two parts, 42063 and 6521, that added together give a palindrome (48584).

The spelling of 420636521 in words is "four hundred twenty million, six hundred thirty-six thousand, five hundred twenty-one".