40002021 has 6 divisors (see below), whose sum is σ = 57780710. Its totient is φ = 26668008.

The previous prime is 40001999. The next prime is 40002023. The reversal of 40002021 is 12020004.

It can be written as a sum of positive squares in only one way, i.e., 30305025 + 9696996 = 5505^2 + 3114^2 .

It is not a de Polignac number, because 40002021 - 2⁶ = 40001957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 4444669 = 40002021 / (4 + 0 + 0 + 0 + 2 + 0 + 2 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 40001994 and 40002012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40002023) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2222326 + ... + 2222343.

Almost surely, 2^40002021 is an apocalyptic number.

It is an amenable number.

40002021 is a deficient number, since it is larger than the sum of its proper divisors (17778689).

40002021 is a wasteful number, since it uses less digits than its factorization.

40002021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4444675 (or 4444672 counting only the distinct ones).

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

The square root of 40002021 is about 6324.7150923974. The cubic root of 40002021 is about 342.0009490073. Note that the first 3 decimals are identical.

Adding to 40002021 its reverse (12020004), we get a palindrome (52022025).

The spelling of 40002021 in words is "forty million, two thousand, twenty-one".