40020021 has 16 divisors (see below), whose sum is σ = 59393920. Its totient is φ = 26632800.

The previous prime is 40020017. The next prime is 40020037. The reversal of 40020021 is 12002004.

It is not a de Polignac number, because 40020021 - 2² = 40020017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 40019985 and 40020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40020011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21321 + ... + 23121.

It is an arithmetic number, because the mean of its divisors is an integer number (3712120).

Almost surely, 2^40020021 is an apocalyptic number.

It is an amenable number.

40020021 is a deficient number, since it is larger than the sum of its proper divisors (19373899).

40020021 is a wasteful number, since it uses less digits than its factorization.

40020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2633 (or 2627 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 40020021 is about 6326.1379213545. The cubic root of 40020021 is about 342.0522388655.

Adding to 40020021 its reverse (12002004), we get a palindrome (52022025).

The spelling of 40020021 in words is "forty million, twenty thousand, twenty-one".