661421330 has 16 divisors (see below), whose sum is σ = 1195089984. Its totient is φ = 263561520.

The previous prime is 661421317. The next prime is 661421333. The reversal of 661421330 is 33124166.

It is a self number, because there is not a number n which added to its sum of digits gives 661421330.

It is not an unprimeable number, because it can be changed into a prime (661421333) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 123116 + ... + 128375.

It is an arithmetic number, because the mean of its divisors is an integer number (74693124).

Almost surely, 2^661421330 is an apocalyptic number.

661421330 is a deficient number, since it is larger than the sum of its proper divisors (533668654).

661421330 is a wasteful number, since it uses less digits than its factorization.

661421330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251761.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 661421330 is about 25718.1128778921. The cubic root of 661421330 is about 871.2833176846.

Adding to 661421330 its reverse (33124166), we get a palindrome (694545496).

The spelling of 661421330 in words is "six hundred sixty-one million, four hundred twenty-one thousand, three hundred thirty".