642121069 has 4 divisors (see below), whose sum is σ = 642193920. Its totient is φ = 642048220.

The previous prime is 642121043. The next prime is 642121087. The reversal of 642121069 is 960121246.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 642121069 - 2⁵ = 642121037 is a prime.

It is a super-3 number, since 3×642121069³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642121069.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642121009) 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, 21037 + ... + 41554.

It is an arithmetic number, because the mean of its divisors is an integer number (160548480).

Almost surely, 2^642121069 is an apocalyptic number.

It is an amenable number.

642121069 is a deficient number, since it is larger than the sum of its proper divisors (72851).

642121069 is a wasteful number, since it uses less digits than its factorization.

642121069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72850.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 642121069 is about 25340.1079121617. The cubic root of 642121069 is about 862.7248480228.

The spelling of 642121069 in words is "six hundred forty-two million, one hundred twenty-one thousand, sixty-nine".