661421329 has 12 divisors (see below), whose sum is σ = 712463364. Its totient is φ = 611908352.

The previous prime is 661421317. The next prime is 661421333. The reversal of 661421329 is 923124166.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 548636929 + 112784400 = 23423^2 + 10620^2 .

It is not a de Polignac number, because 661421329 - 2⁵ = 661421297 is a prime.

It is a super-2 number, since 2×661421329² = 874956348912252482, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661421294 and 661421303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661421429) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 53589 + ... + 64765.

It is an arithmetic number, because the mean of its divisors is an integer number (59371947).

Almost surely, 2^661421329 is an apocalyptic number.

It is an amenable number.

661421329 is a deficient number, since it is larger than the sum of its proper divisors (51042035).

661421329 is a wasteful number, since it uses less digits than its factorization.

661421329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11312 (or 11253 counting only the distinct ones).

The product of its digits is 15552, while the sum is 34.

The square root of 661421329 is about 25718.1128584506. The cubic root of 661421329 is about 871.2833172455.

The spelling of 661421329 in words is "six hundred sixty-one million, four hundred twenty-one thousand, three hundred twenty-nine".