642491537 has 4 divisors (see below), whose sum is σ = 646041396. Its totient is φ = 638941680.

The previous prime is 642491527. The next prime is 642491639. The reversal of 642491537 is 735194246.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 183846481 + 458645056 = 13559^2 + 21416^2 .

It is a cyclic number.

It is not a de Polignac number, because 642491537 - 2²⁰ = 641442961 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642491494 and 642491503.

It is not an unprimeable number, because it can be changed into a prime (642491527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1774658 + ... + 1775019.

It is an arithmetic number, because the mean of its divisors is an integer number (161510349).

Almost surely, 2^642491537 is an apocalyptic number.

It is an amenable number.

642491537 is a deficient number, since it is larger than the sum of its proper divisors (3549859).

642491537 is a wasteful number, since it uses less digits than its factorization.

642491537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3549858.

The product of its digits is 181440, while the sum is 41.

The square root of 642491537 is about 25347.4167717344. The cubic root of 642491537 is about 862.8907308124.

The spelling of 642491537 in words is "six hundred forty-two million, four hundred ninety-one thousand, five hundred thirty-seven".