6421239990 has 48 divisors (see below), whose sum is σ = 18212974416. Its totient is φ = 1556664000.

The previous prime is 6421239977. The next prime is 6421239991. The reversal of 6421239990 is 999321246.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6421239991) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3242061 + ... + 3244040.

It is an arithmetic number, because the mean of its divisors is an integer number (379436967).

Almost surely, 2^6421239990 is an apocalyptic number.

6421239990 is an abundant number, since it is smaller than the sum of its proper divisors (11791734426).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6421239990 is a wasteful number, since it uses less digits than its factorization.

6421239990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6486125 (or 6486122 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 45.

The square root of 6421239990 is about 80132.6399789749. The cubic root of 6421239990 is about 1858.6871675889.

The spelling of 6421239990 in words is "six billion, four hundred twenty-one million, two hundred thirty-nine thousand, nine hundred ninety".