642126251 has 4 divisors (see below), whose sum is σ = 691520592. Its totient is φ = 592731912.

The previous prime is 642126241. The next prime is 642126257. The reversal of 642126251 is 152621246.

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

It is a cyclic number.

It is not a de Polignac number, because 642126251 - 2⁶ = 642126187 is a prime.

It is a super-2 number, since 2×642126251² = 824652244446630002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642126257) 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, 24697151 + ... + 24697176.

It is an arithmetic number, because the mean of its divisors is an integer number (172880148).

Almost surely, 2^642126251 is an apocalyptic number.

642126251 is a deficient number, since it is larger than the sum of its proper divisors (49394341).

642126251 is a wasteful number, since it uses less digits than its factorization.

642126251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49394340.

The product of its digits is 5760, while the sum is 29.

The square root of 642126251 is about 25340.2101609280. The cubic root of 642126251 is about 862.7271687835.

Adding to 642126251 its reverse (152621246), we get a palindrome (794747497).

The spelling of 642126251 in words is "six hundred forty-two million, one hundred twenty-six thousand, two hundred fifty-one".