2440400021 has 2 divisors, whose sum is σ = 2440400022. Its totient is φ = 2440400020.

The previous prime is 2440399961. The next prime is 2440400041. The reversal of 2440400021 is 1200040442.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2219728996 + 220671025 = 47114^2 + 14855^2 .

It is a cyclic number.

It is not a de Polignac number, because 2440400021 - 2¹⁴ = 2440383637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2440400041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1220200010 + 1220200011.

It is an arithmetic number, because the mean of its divisors is an integer number (1220200011).

Almost surely, 2^2440400021 is an apocalyptic number.

It is an amenable number.

2440400021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2440400021 is an equidigital number, since it uses as much as digits as its factorization.

2440400021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 2440400021 is about 49400.4050691895. The cubic root of 2440400021 is about 1346.3366655848.

Adding to 2440400021 its reverse (1200040442), we get a palindrome (3640440463).

The spelling of 2440400021 in words is "two billion, four hundred forty million, four hundred thousand, twenty-one".