240420400021 has 4 divisors (see below), whose sum is σ = 240881860044. Its totient is φ = 239958940000.

The previous prime is 240420399991. The next prime is 240420400057. The reversal of 240420400021 is 120004024042.

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 119222421796 + 121197978225 = 345286^2 + 348135^2 .

It is a cyclic number.

It is not a de Polignac number, because 240420400021 - 2³⁷ = 102981446549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (240420400421) 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, 230729230 + ... + 230730271.

It is an arithmetic number, because the mean of its divisors is an integer number (60220465011).

Almost surely, 2^240420400021 is an apocalyptic number.

It is an amenable number.

240420400021 is a deficient number, since it is larger than the sum of its proper divisors (461460023).

240420400021 is an equidigital number, since it uses as much as digits as its factorization.

240420400021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 461460022.

The product of its (nonzero) digits is 512, while the sum is 19.

Adding to 240420400021 its reverse (120004024042), we get a palindrome (360424424063).

The spelling of 240420400021 in words is "two hundred forty billion, four hundred twenty million, four hundred thousand, twenty-one".