642036251 has 4 divisors (see below), whose sum is σ = 642154272. Its totient is φ = 641918232.

The previous prime is 642036211. The next prime is 642036253. The reversal of 642036251 is 152630246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 152630246 = 2 ⋅76315123.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642036251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642036253) 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, 50435 + ... + 61868.

It is an arithmetic number, because the mean of its divisors is an integer number (160538568).

Almost surely, 2^642036251 is an apocalyptic number.

642036251 is a deficient number, since it is larger than the sum of its proper divisors (118021).

642036251 is a wasteful number, since it uses less digits than its factorization.

642036251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118020.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 642036251 is about 25338.4342649659. The cubic root of 642036251 is about 862.6868604730.

Adding to 642036251 its reverse (152630246), we get a palindrome (794666497).

The spelling of 642036251 in words is "six hundred forty-two million, thirty-six thousand, two hundred fifty-one".