642778401 has 32 divisors (see below), whose sum is σ = 910540800. Its totient is φ = 402519744.

The previous prime is 642778399. The next prime is 642778403. The reversal of 642778401 is 104877246.

It is an interprime number because it is at equal distance from previous prime (642778399) and next prime (642778403).

It is not a de Polignac number, because 642778401 - 2¹ = 642778399 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 642778401.

It is not an unprimeable number, because it can be changed into a prime (642778403) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1058640 + ... + 1059246.

It is an arithmetic number, because the mean of its divisors is an integer number (28454400).

Almost surely, 2^642778401 is an apocalyptic number.

It is an amenable number.

642778401 is a deficient number, since it is larger than the sum of its proper divisors (267762399).

642778401 is a wasteful number, since it uses less digits than its factorization.

642778401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 885.

The product of its (nonzero) digits is 75264, while the sum is 39.

The square root of 642778401 is about 25353.0747839389. The cubic root of 642778401 is about 863.0191348154.

The spelling of 642778401 in words is "six hundred forty-two million, seven hundred seventy-eight thousand, four hundred one".