642441551 has 4 divisors (see below), whose sum is σ = 663165504. Its totient is φ = 621717600.

The previous prime is 642441539. The next prime is 642441559. The reversal of 642441551 is 155144246.

642441551 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.

It is a cyclic number.

It is not a de Polignac number, because 642441551 - 2¹⁸ = 642179407 is a prime.

It is a super-2 number, since 2×642441551² = 825462292902571202, 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 (642441559) 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, 10361930 + ... + 10361991.

It is an arithmetic number, because the mean of its divisors is an integer number (165791376).

Almost surely, 2^642441551 is an apocalyptic number.

642441551 is a deficient number, since it is larger than the sum of its proper divisors (20723953).

642441551 is a wasteful number, since it uses less digits than its factorization.

642441551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20723952.

The product of its digits is 19200, while the sum is 32.

The square root of 642441551 is about 25346.4307349181. The cubic root of 642441551 is about 862.8683525282.

Adding to 642441551 its reverse (155144246), we get a palindrome (797585797).

The spelling of 642441551 in words is "six hundred forty-two million, four hundred forty-one thousand, five hundred fifty-one".