420015661 has 4 divisors (see below), whose sum is σ = 452324572. Its totient is φ = 387706752.

The previous prime is 420015643. The next prime is 420015667. The reversal of 420015661 is 166510024.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56160036 + 363855625 = 7494^2 + 19075^2 .

It is a cyclic number.

It is not a de Polignac number, because 420015661 - 2¹¹ = 420013613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (420015667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16154436 + ... + 16154461.

It is an arithmetic number, because the mean of its divisors is an integer number (113081143).

Almost surely, 2^420015661 is an apocalyptic number.

It is an amenable number.

420015661 is a deficient number, since it is larger than the sum of its proper divisors (32308911).

420015661 is a wasteful number, since it uses less digits than its factorization.

420015661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32308910.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 420015661 is about 20494.2836176335. The cubic root of 420015661 is about 748.8965467991.

Adding to 420015661 its reverse (166510024), we get a palindrome (586525685).

The spelling of 420015661 in words is "four hundred twenty million, fifteen thousand, six hundred sixty-one".