21440434404491 has 2 divisors, whose sum is σ = 21440434404492. Its totient is φ = 21440434404490.

The previous prime is 21440434404461. The next prime is 21440434404511. The reversal of 21440434404491 is 19440443404412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21440434404491 is a prime.

It is not a weakly prime, because it can be changed into another prime (21440434404421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720217202245 + 10720217202246.

It is an arithmetic number, because the mean of its divisors is an integer number (10720217202246).

Almost surely, 2^{21440434404491} is an apocalyptic number.

21440434404491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440434404491 is an equidigital number, since it uses as much as digits as its factorization.

21440434404491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 884736, while the sum is 44.

The spelling of 21440434404491 in words is "twenty-one trillion, four hundred forty billion, four hundred thirty-four million, four hundred four thousand, four hundred ninety-one".