642154721531 has 2 divisors, whose sum is σ = 642154721532. Its totient is φ = 642154721530.

The previous prime is 642154721491. The next prime is 642154721557. The reversal of 642154721531 is 135127451246.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642154721531 - 2³⁴ = 624974852347 is a prime.

It is a super-2 number, since 2×642154721531² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (642154721561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321077360765 + 321077360766.

It is an arithmetic number, because the mean of its divisors is an integer number (321077360766).

Almost surely, 2^642154721531 is an apocalyptic number.

642154721531 is a deficient number, since it is larger than the sum of its proper divisors (1).

642154721531 is an equidigital number, since it uses as much as digits as its factorization.

642154721531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 201600, while the sum is 41.

The spelling of 642154721531 in words is "six hundred forty-two billion, one hundred fifty-four million, seven hundred twenty-one thousand, five hundred thirty-one".