1664020413561 has 16 divisors (see below), whose sum is σ = 2421302353920. Its totient is φ = 1008118459920.

The previous prime is 1664020413541. The next prime is 1664020413571. The reversal of 1664020413561 is 1653140204661.

It is not a de Polignac number, because 1664020413561 - 2²⁶ = 1663953304697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1664020413541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9379801 + ... + 9555558.

It is an arithmetic number, because the mean of its divisors is an integer number (151331397120).

Almost surely, 2^{1664020413561} is an apocalyptic number.

1664020413561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1664020413561 is a deficient number, since it is larger than the sum of its proper divisors (757281940359).

1664020413561 is a wasteful number, since it uses less digits than its factorization.

1664020413561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18938036.

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 1664020413561 in words is "one trillion, six hundred sixty-four billion, twenty million, four hundred thirteen thousand, five hundred sixty-one".