642222251 has 4 divisors (see below), whose sum is σ = 700606104. Its totient is φ = 583838400.

The previous prime is 642222247. The next prime is 642222263. The reversal of 642222251 is 152222246.

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 642222251 - 2² = 642222247 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642222251.

It is not an unprimeable number, because it can be changed into a prime (642222281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29191910 + ... + 29191931.

It is an arithmetic number, because the mean of its divisors is an integer number (175151526).

Almost surely, 2^642222251 is an apocalyptic number.

642222251 is a deficient number, since it is larger than the sum of its proper divisors (58383853).

642222251 is a wasteful number, since it uses less digits than its factorization.

642222251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58383852.

The product of its digits is 3840, while the sum is 26.

The square root of 642222251 is about 25342.1043127835. The cubic root of 642222251 is about 862.7701601636.

Adding to 642222251 its reverse (152222246), we get a palindrome (794444497).

The spelling of 642222251 in words is "six hundred forty-two million, two hundred twenty-two thousand, two hundred fifty-one".