21440242247 has 2 divisors, whose sum is σ = 21440242248. Its totient is φ = 21440242246.

The previous prime is 21440242211. The next prime is 21440242267. The reversal of 21440242247 is 74224204412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21440242247 - 2⁶ = 21440242183 is a prime.

It is a super-2 number, since 2×21440242247² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21440242267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720121123 + 10720121124.

It is an arithmetic number, because the mean of its divisors is an integer number (10720121124).

Almost surely, 2^21440242247 is an apocalyptic number.

21440242247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440242247 is an equidigital number, since it uses as much as digits as its factorization.

21440242247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28672, while the sum is 32.

Adding to 21440242247 its reverse (74224204412), we get a palindrome (95664446659).

The spelling of 21440242247 in words is "twenty-one billion, four hundred forty million, two hundred forty-two thousand, two hundred forty-seven".