642567557521 has 2 divisors, whose sum is σ = 642567557522. Its totient is φ = 642567557520.

The previous prime is 642567557503. The next prime is 642567557531. The reversal of 642567557521 is 125755765246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 501575568400 + 140991989121 = 708220^2 + 375489^2 .

It is a cyclic number.

It is not a de Polignac number, because 642567557521 - 2³¹ = 640420073873 is a prime.

It is not a weakly prime, because it can be changed into another prime (642567557531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321283778760 + 321283778761.

It is an arithmetic number, because the mean of its divisors is an integer number (321283778761).

Almost surely, 2^642567557521 is an apocalyptic number.

It is an amenable number.

642567557521 is a deficient number, since it is larger than the sum of its proper divisors (1).

642567557521 is an equidigital number, since it uses as much as digits as its factorization.

642567557521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17640000, while the sum is 55.

The spelling of 642567557521 in words is "six hundred forty-two billion, five hundred sixty-seven million, five hundred fifty-seven thousand, five hundred twenty-one".