642822861 has 4 divisors (see below), whose sum is σ = 857097152. Its totient is φ = 428548572.

The previous prime is 642822833. The next prime is 642822863. The reversal of 642822861 is 168228246.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 642822861 - 2¹⁸ = 642560717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642822863) 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, 107137141 + ... + 107137146.

It is an arithmetic number, because the mean of its divisors is an integer number (214274288).

Almost surely, 2^642822861 is an apocalyptic number.

It is an amenable number.

642822861 is a deficient number, since it is larger than the sum of its proper divisors (214274291).

642822861 is a wasteful number, since it uses less digits than its factorization.

642822861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214274290.

The product of its digits is 73728, while the sum is 39.

The square root of 642822861 is about 25353.9515855024. The cubic root of 642822861 is about 863.0390322617.

The spelling of 642822861 in words is "six hundred forty-two million, eight hundred twenty-two thousand, eight hundred sixty-one".