661003223513021 has 8 divisors (see below), whose sum is σ = 677283719542584. Its totient is φ = 644730273492480.

The previous prime is 661003223513011. The next prime is 661003223513033. The reversal of 661003223513021 is 120315322300166.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1478933260996 + 659524290252025 = 1216114^2 + 25681205^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661003223513021 is a prime.

It is a super-2 number, since 2×661003223513021² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661003223513011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1886324906 + ... + 1886675291.

It is an arithmetic number, because the mean of its divisors is an integer number (84660464942823).

Almost surely, 2^{661003223513021} is an apocalyptic number.

It is an amenable number.

661003223513021 is a deficient number, since it is larger than the sum of its proper divisors (16280496029563).

661003223513021 is a wasteful number, since it uses less digits than its factorization.

661003223513021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3773004511.

The product of its (nonzero) digits is 38880, while the sum is 35.

Adding to 661003223513021 its reverse (120315322300166), we get a palindrome (781318545813187).

The spelling of 661003223513021 in words is "six hundred sixty-one trillion, three billion, two hundred twenty-three million, five hundred thirteen thousand, twenty-one".