642646646237 has 2 divisors, whose sum is σ = 642646646238. Its totient is φ = 642646646236.

The previous prime is 642646646203. The next prime is 642646646267. The reversal of 642646646237 is 732646646246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 400099261156 + 242547385081 = 632534^2 + 492491^2 .

It is a cyclic number.

It is not a de Polignac number, because 642646646237 - 2²⁸ = 642378210781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642646646267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321323323118 + 321323323119.

It is an arithmetic number, because the mean of its divisors is an integer number (321323323119).

Almost surely, 2^642646646237 is an apocalyptic number.

It is an amenable number.

642646646237 is a deficient number, since it is larger than the sum of its proper divisors (1).

642646646237 is an equidigital number, since it uses as much as digits as its factorization.

642646646237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41803776, while the sum is 56.

Subtracting 642646646237 from its reverse (732646646246), we obtain a palindrome (90000000009).

The spelling of 642646646237 in words is "six hundred forty-two billion, six hundred forty-six million, six hundred forty-six thousand, two hundred thirty-seven".