642921251 has 8 divisors (see below), whose sum is σ = 751855104. Its totient is φ = 538259400.

The previous prime is 642921241. The next prime is 642921269. The reversal of 642921251 is 152129246.

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

It is not a de Polignac number, because 642921251 - 2²² = 638726947 is a prime.

It is not an unprimeable number, because it can be changed into a prime (642921211) 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 7 ways as a sum of consecutive naturals, for example, 1067675 + ... + 1068276.

It is an arithmetic number, because the mean of its divisors is an integer number (93981888).

Almost surely, 2^642921251 is an apocalyptic number.

642921251 is a deficient number, since it is larger than the sum of its proper divisors (108933853).

642921251 is a wasteful number, since it uses less digits than its factorization.

642921251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2136001.

The product of its digits is 8640, while the sum is 32.

The square root of 642921251 is about 25355.8918399649. The cubic root of 642921251 is about 863.0830620578.

The spelling of 642921251 in words is "six hundred forty-two million, nine hundred twenty-one thousand, two hundred fifty-one".