21204440351 has 2 divisors, whose sum is σ = 21204440352. Its totient is φ = 21204440350.

The previous prime is 21204440339. The next prime is 21204440381. The reversal of 21204440351 is 15304440212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21204440351 - 2²² = 21200246047 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21204440351.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21204440381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602220175 + 10602220176.

It is an arithmetic number, because the mean of its divisors is an integer number (10602220176).

Almost surely, 2^21204440351 is an apocalyptic number.

21204440351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21204440351 is an equidigital number, since it uses as much as digits as its factorization.

21204440351 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21204440351 its reverse (15304440212), we get a palindrome (36508880563).

The spelling of 21204440351 in words is "twenty-one billion, two hundred four million, four hundred forty thousand, three hundred fifty-one".