642472918261 has 4 divisors (see below), whose sum is σ = 676287282400. Its totient is φ = 608658554124.

The previous prime is 642472918201. The next prime is 642472918291. The reversal of 642472918261 is 162819274246.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 162819274246 = 2 ⋅81409637123.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642472918261 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642472918199 and 642472918208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642472918201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16907182041 + ... + 16907182078.

It is an arithmetic number, because the mean of its divisors is an integer number (169071820600).

Almost surely, 2^642472918261 is an apocalyptic number.

It is an amenable number.

642472918261 is a deficient number, since it is larger than the sum of its proper divisors (33814364139).

642472918261 is a wasteful number, since it uses less digits than its factorization.

642472918261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33814364138.

The product of its digits is 2322432, while the sum is 52.

The spelling of 642472918261 in words is "six hundred forty-two billion, four hundred seventy-two million, nine hundred eighteen thousand, two hundred sixty-one".