640106421 has 8 divisors (see below), whose sum is σ = 861452064. Its totient is φ = 422749200.

The previous prime is 640106377. The next prime is 640106431. The reversal of 640106421 is 124601046.

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

It is not a de Polignac number, because 640106421 - 2⁷ = 640106293 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640106391 and 640106400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640106431) 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, 996730 + ... + 997371.

It is an arithmetic number, because the mean of its divisors is an integer number (107681508).

Almost surely, 2^640106421 is an apocalyptic number.

It is an amenable number.

640106421 is a deficient number, since it is larger than the sum of its proper divisors (221345643).

640106421 is a wasteful number, since it uses less digits than its factorization.

640106421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1994211.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 640106421 is about 25300.3245236104. The cubic root of 640106421 is about 861.8216394267.

Adding to 640106421 its reverse (124601046), we get a palindrome (764707467).

The spelling of 640106421 in words is "six hundred forty million, one hundred six thousand, four hundred twenty-one".