642254711521 has 8 divisors (see below), whose sum is σ = 687045066120. Its totient is φ = 598243319808.

The previous prime is 642254711513. The next prime is 642254711557. The reversal of 642254711521 is 125117452246.

It can be written as a sum of positive squares in 4 ways, for example, as 84006645921 + 558248065600 = 289839^2 + 747160^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642254711521 - 2³ = 642254711513 is a prime.

It is a super-2 number, since 2×642254711521² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642254711221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 194739016 + ... + 194742313.

It is an arithmetic number, because the mean of its divisors is an integer number (85880633265).

Almost surely, 2^642254711521 is an apocalyptic number.

It is an amenable number.

642254711521 is a deficient number, since it is larger than the sum of its proper divisors (44790354599).

642254711521 is a wasteful number, since it uses less digits than its factorization.

642254711521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389481443.

The product of its digits is 134400, while the sum is 40.

The spelling of 642254711521 in words is "six hundred forty-two billion, two hundred fifty-four million, seven hundred eleven thousand, five hundred twenty-one".