642952781 has 4 divisors (see below), whose sum is σ = 645643200. Its totient is φ = 640262364.

The previous prime is 642952753. The next prime is 642952789. The reversal of 642952781 is 187259246.

It is a happy number.

642952781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a cyclic number.

It is not a de Polignac number, because 642952781 - 2¹⁴ = 642936397 is a prime.

It is a super-2 number, since 2×642952781² = 826776557191267922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642952789) 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, 1344851 + ... + 1345328.

It is an arithmetic number, because the mean of its divisors is an integer number (161410800).

Almost surely, 2^642952781 is an apocalyptic number.

It is an amenable number.

642952781 is a deficient number, since it is larger than the sum of its proper divisors (2690419).

642952781 is a wasteful number, since it uses less digits than its factorization.

642952781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2690418.

The product of its digits is 241920, while the sum is 44.

The square root of 642952781 is about 25356.5135813266. The cubic root of 642952781 is about 863.0971708692.

It can be divided in two parts, 64295 and 2781, that added together give a palindrome (67076).

The spelling of 642952781 in words is "six hundred forty-two million, nine hundred fifty-two thousand, seven hundred eighty-one".