642774409 has 2 divisors, whose sum is σ = 642774410. Its totient is φ = 642774408.

The previous prime is 642774347. The next prime is 642774421. The reversal of 642774409 is 904477246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 563920009 + 78854400 = 23747^2 + 8880^2 .

It is a cyclic number.

It is not a de Polignac number, because 642774409 - 2¹³ = 642766217 is a prime.

It is not a weakly prime, because it can be changed into another prime (642774439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321387204 + 321387205.

It is an arithmetic number, because the mean of its divisors is an integer number (321387205).

Almost surely, 2^642774409 is an apocalyptic number.

It is an amenable number.

642774409 is a deficient number, since it is larger than the sum of its proper divisors (1).

642774409 is an equidigital number, since it uses as much as digits as its factorization.

642774409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 338688, while the sum is 43.

The square root of 642774409 is about 25352.9960556933. The cubic root of 642774409 is about 863.0173482072.

It can be divided in two parts, 64277 and 4409, that added together give a palindrome (68686).

The spelling of 642774409 in words is "six hundred forty-two million, seven hundred seventy-four thousand, four hundred nine".