21478138211 has 2 divisors, whose sum is σ = 21478138212. Its totient is φ = 21478138210.

The previous prime is 21478138091. The next prime is 21478138217. The reversal of 21478138211 is 11283187412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21478138211 is a prime.

It is a super-2 number, since 2×21478138211² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21478138217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10739069105 + 10739069106.

It is an arithmetic number, because the mean of its divisors is an integer number (10739069106).

Almost surely, 2^21478138211 is an apocalyptic number.

21478138211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21478138211 is an equidigital number, since it uses as much as digits as its factorization.

21478138211 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21504, while the sum is 38.

The spelling of 21478138211 in words is "twenty-one billion, four hundred seventy-eight million, one hundred thirty-eight thousand, two hundred eleven".