661428417 has 8 divisors (see below), whose sum is σ = 949743424. Its totient is φ = 407032848.

The previous prime is 661428407. The next prime is 661428479. The reversal of 661428417 is 714824166.

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

It is not a de Polignac number, because 661428417 - 2⁸ = 661428161 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39), and also a Moran number because the ratio is a prime number: 16959703 = 661428417 / (6 + 6 + 1 + 4 + 2 + 8 + 4 + 1 + 7).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661428407) 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, 8479813 + ... + 8479890.

It is an arithmetic number, because the mean of its divisors is an integer number (118717928).

Almost surely, 2^661428417 is an apocalyptic number.

It is an amenable number.

661428417 is a deficient number, since it is larger than the sum of its proper divisors (288315007).

661428417 is a wasteful number, since it uses less digits than its factorization.

661428417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16959719.

The product of its digits is 64512, while the sum is 39.

The square root of 661428417 is about 25718.2506597941. The cubic root of 661428417 is about 871.2864295501.

The spelling of 661428417 in words is "six hundred sixty-one million, four hundred twenty-eight thousand, four hundred seventeen".