661197021 has 8 divisors (see below), whose sum is σ = 883350720. Its totient is φ = 439920672.

The previous prime is 661196999. The next prime is 661197041. The reversal of 661197021 is 120791166.

661197021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 661197021 - 2¹⁵ = 661164253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661197041) 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, 217576 + ... + 220593.

It is an arithmetic number, because the mean of its divisors is an integer number (110418840).

Almost surely, 2^661197021 is an apocalyptic number.

It is an amenable number.

661197021 is a deficient number, since it is larger than the sum of its proper divisors (222153699).

661197021 is a wasteful number, since it uses less digits than its factorization.

661197021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 438675.

The product of its (nonzero) digits is 4536, while the sum is 33.

The square root of 661197021 is about 25713.7515932623. The cubic root of 661197021 is about 871.1848132578.

The spelling of 661197021 in words is "six hundred sixty-one million, one hundred ninety-seven thousand, twenty-one".