40398640 has 20 divisors (see below), whose sum is σ = 93927024. Its totient is φ = 16159424.

The previous prime is 40398583. The next prime is 40398643. The reversal of 40398640 is 4689304.

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×40398640² = 3264100227699200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 40398596 and 40398605.

It is not an unprimeable number, because it can be changed into a prime (40398643) 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, 252412 + ... + 252571.

Almost surely, 2^40398640 is an apocalyptic number.

40398640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

40398640 is an abundant number, since it is smaller than the sum of its proper divisors (53528384).

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

40398640 is a wasteful number, since it uses less digits than its factorization.

40398640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504996 (or 504990 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 40398640 is about 6355.9924480761. The cubic root of 40398640 is about 343.1275439619.

The spelling of 40398640 in words is "forty million, three hundred ninety-eight thousand, six hundred forty".