1646400666505 has 32 divisors (see below), whose sum is σ = 2314168704000. Its totient is φ = 1101007541760.

The previous prime is 1646400666487. The next prime is 1646400666509. The reversal of 1646400666505 is 5056660046461.

It is a happy number.

It is not a de Polignac number, because 1646400666505 - 2⁷ = 1646400666377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1646400666509) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1318630 + ... + 2243119.

It is an arithmetic number, because the mean of its divisors is an integer number (72317772000).

Almost surely, 2^{1646400666505} is an apocalyptic number.

It is an amenable number.

1646400666505 is a deficient number, since it is larger than the sum of its proper divisors (667768037495).

1646400666505 is a wasteful number, since it uses less digits than its factorization.

1646400666505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3562089.

The product of its (nonzero) digits is 3110400, while the sum is 49.

The spelling of 1646400666505 in words is "one trillion, six hundred forty-six billion, four hundred million, six hundred sixty-six thousand, five hundred five".