664567561220421 has 16 divisors (see below), whose sum is σ = 886188548947968. Its totient is φ = 442995808950000.

The previous prime is 664567561220369. The next prime is 664567561220443. The reversal of 664567561220421 is 124022165765466.

664567561220421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 664567561220421 - 2⁶ = 664567561220357 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664567561220461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1716720316 + ... + 1717107386.

It is an arithmetic number, because the mean of its divisors is an integer number (55386784309248).

Almost surely, 2^{664567561220421} is an apocalyptic number.

It is an amenable number.

664567561220421 is a deficient number, since it is larger than the sum of its proper divisors (221620987727547).

664567561220421 is a wasteful number, since it uses less digits than its factorization.

664567561220421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 449192.

The product of its (nonzero) digits is 29030400, while the sum is 57.

The spelling of 664567561220421 in words is "six hundred sixty-four trillion, five hundred sixty-seven billion, five hundred sixty-one million, two hundred twenty thousand, four hundred twenty-one".