21440434404421 has 2 divisors, whose sum is σ = 21440434404422. Its totient is φ = 21440434404420.

The previous prime is 21440434404341. The next prime is 21440434404461. The reversal of 21440434404421 is 12440443404412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21036771135396 + 403663269025 = 4586586^2 + 635345^2 .

It is a cyclic number.

It is not a de Polignac number, because 21440434404421 - 2⁹ = 21440434403909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21440434404461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720217202210 + 10720217202211.

It is an arithmetic number, because the mean of its divisors is an integer number (10720217202211).

Almost surely, 2^{21440434404421} is an apocalyptic number.

It is an amenable number.

21440434404421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440434404421 is an equidigital number, since it uses as much as digits as its factorization.

21440434404421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 196608, while the sum is 37.

Adding to 21440434404421 its reverse (12440443404412), we get a palindrome (33880877808833).

The spelling of 21440434404421 in words is "twenty-one trillion, four hundred forty billion, four hundred thirty-four million, four hundred four thousand, four hundred twenty-one".