642551421 has 8 divisors (see below), whose sum is σ = 860510304. Its totient is φ = 426480080.

The previous prime is 642551419. The next prime is 642551447. The reversal of 642551421 is 124155246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642551421 - 2¹ = 642551419 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642551411) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 471090 + ... + 472451.

It is an arithmetic number, because the mean of its divisors is an integer number (107563788).

Almost surely, 2^642551421 is an apocalyptic number.

It is an amenable number.

642551421 is a deficient number, since it is larger than the sum of its proper divisors (217958883).

642551421 is a wasteful number, since it uses less digits than its factorization.

642551421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 943771.

The product of its digits is 9600, while the sum is 30.

The square root of 642551421 is about 25348.5980085684. The cubic root of 642551421 is about 862.9175388144.

The spelling of 642551421 in words is "six hundred forty-two million, five hundred fifty-one thousand, four hundred twenty-one".