661661005 has 8 divisors (see below), whose sum is σ = 794401632. Its totient is φ = 529056528.

The previous prime is 661660969. The next prime is 661661009. The reversal of 661661005 is 500166166.

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

It is a cyclic number.

It is not a de Polignac number, because 661661005 - 2¹³ = 661652813 is a prime.

It is a super-2 number, since 2×661661005² = 875590571075220050, which 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 (661661009) 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, 23019 + ... + 43048.

It is an arithmetic number, because the mean of its divisors is an integer number (99300204).

Almost surely, 2^661661005 is an apocalyptic number.

It is an amenable number.

661661005 is a deficient number, since it is larger than the sum of its proper divisors (132740627).

661661005 is a wasteful number, since it uses less digits than its factorization.

661661005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68075.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 661661005 is about 25722.7721095530. The cubic root of 661661005 is about 871.3885454223.

The spelling of 661661005 in words is "six hundred sixty-one million, six hundred sixty-one thousand, five".