2638979640 has 192 divisors, whose sum is σ = 9382988160. Its totient is φ = 637935360.

The previous prime is 2638979633. The next prime is 2638979689. The reversal of 2638979640 is 469798362.

It is a happy number.

It is a Cunningham number, because it is equal to 51371²-1.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1848607 + ... + 1850033.

It is an arithmetic number, because the mean of its divisors is an integer number (48869730).

Almost surely, 2^2638979640 is an apocalyptic number.

2638979640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2638979640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4691494080).

2638979640 is an abundant number, since it is smaller than the sum of its proper divisors (6744008520).

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

2638979640 is a wasteful number, since it uses less digits than its factorization.

2638979640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1922 (or 1915 counting only the distinct ones).

The product of its (nonzero) digits is 3919104, while the sum is 54.

The square root of 2638979640 is about 51370.9999902669. Note that the first 5 decimals coincide. The cubic root of 2638979640 is about 1381.9065644855.

The spelling of 2638979640 in words is "two billion, six hundred thirty-eight million, nine hundred seventy-nine thousand, six hundred forty".