21738970447 has 2 divisors, whose sum is σ = 21738970448. Its totient is φ = 21738970446.

The previous prime is 21738970381. The next prime is 21738970501. The reversal of 21738970447 is 74407983712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21738970447 - 2¹⁵ = 21738937679 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21738970394 and 21738970403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21738971447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10869485223 + 10869485224.

It is an arithmetic number, because the mean of its divisors is an integer number (10869485224).

Almost surely, 2^21738970447 is an apocalyptic number.

21738970447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21738970447 is an equidigital number, since it uses as much as digits as its factorization.

21738970447 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2370816, while the sum is 52.

The spelling of 21738970447 in words is "twenty-one billion, seven hundred thirty-eight million, nine hundred seventy thousand, four hundred forty-seven".