4000000021 has 4 divisors (see below), whose sum is σ = 4017467500. Its totient is φ = 3982532544.

The previous prime is 4000000019. The next prime is 4000000063. The reversal of 4000000021 is 1200000004.

4000000021 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1827135025 + 2172864996 = 42745^2 + 46614^2 .

It is a cyclic number.

It is not a de Polignac number, because 4000000021 - 2¹ = 4000000019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 3999999950 and 4000000013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4000060021) 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, 8733396 + ... + 8733853.

It is an arithmetic number, because the mean of its divisors is an integer number (1004366875).

Almost surely, 2^4000000021 is an apocalyptic number.

It is an amenable number.

4000000021 is a deficient number, since it is larger than the sum of its proper divisors (17467479).

4000000021 is a wasteful number, since it uses less digits than its factorization.

4000000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17467478.

The product of its (nonzero) digits is 8, while the sum is 7.

The square root of 4000000021 is about 63245.5533693872. The cubic root of 4000000021 is about 1587.4010547462.

Adding to 4000000021 its reverse (1200000004), we get a palindrome (5200000025).

The spelling of 4000000021 in words is "four billion, twenty-one", and thus it is an aban number.