642347616820821 has 32 divisors (see below), whose sum is σ = 901715143034880. Its totient is φ = 405614656656000.

The previous prime is 642347616820751. The next prime is 642347616820853. The reversal of 642347616820821 is 128028616743246.

It is not a de Polignac number, because 642347616820821 - 2¹⁴ = 642347616804437 is a prime.

It is a super-2 number, since 2×642347616820821² (a number of 30 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642347616890821) 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, 7891110721 + ... + 7891192121.

It is an arithmetic number, because the mean of its divisors is an integer number (28178598219840).

Almost surely, 2^{642347616820821} is an apocalyptic number.

It is an amenable number.

642347616820821 is a deficient number, since it is larger than the sum of its proper divisors (259367526214059).

642347616820821 is a wasteful number, since it uses less digits than its factorization.

642347616820821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106537.

The product of its (nonzero) digits is 37158912, while the sum is 60.

The spelling of 642347616820821 in words is "six hundred forty-two trillion, three hundred forty-seven billion, six hundred sixteen million, eight hundred twenty thousand, eight hundred twenty-one".