661422421 has 6 divisors (see below), whose sum is σ = 727018166. Its totient is φ = 601293000.

The previous prime is 661422409. The next prime is 661422481. The reversal of 661422421 is 124224166.

It can be written as a sum of positive squares in only one way, i.e., 599564196 + 61858225 = 24486^2 + 7865^2 .

It is not a de Polignac number, because 661422421 - 2¹¹ = 661420373 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661422421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661422481) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2733030 + ... + 2733271.

Almost surely, 2^661422421 is an apocalyptic number.

It is an amenable number.

661422421 is a deficient number, since it is larger than the sum of its proper divisors (65595745).

661422421 is a wasteful number, since it uses less digits than its factorization.

661422421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5466323 (or 5466312 counting only the distinct ones).

The product of its digits is 4608, while the sum is 28.

The square root of 661422421 is about 25718.1340886154. The cubic root of 661422421 is about 871.2837967385.

Adding to 661422421 its reverse (124224166), we get a palindrome (785646587).

The spelling of 661422421 in words is "six hundred sixty-one million, four hundred twenty-two thousand, four hundred twenty-one".