63661021 has 4 divisors (see below), whose sum is σ = 63962944. Its totient is φ = 63359100.

The previous prime is 63660977. The next prime is 63661049. The reversal of 63661021 is 12016636.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 63661021 - 2⁷ = 63660893 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 (63661421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 150645 + ... + 151066.

It is an arithmetic number, because the mean of its divisors is an integer number (15990736).

Almost surely, 2^63661021 is an apocalyptic number.

It is an amenable number.

63661021 is a deficient number, since it is larger than the sum of its proper divisors (301923).

63661021 is a wasteful number, since it uses less digits than its factorization.

63661021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301922.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 63661021 is about 7978.7856845513. The cubic root of 63661021 is about 399.2925432500.

Adding to 63661021 its reverse (12016636), we get a palindrome (75677657).

The spelling of 63661021 in words is "sixty-three million, six hundred sixty-one thousand, twenty-one".