21406213069 has 2 divisors, whose sum is σ = 21406213070. Its totient is φ = 21406213068.

The previous prime is 21406213057. The next prime is 21406213079. The reversal of 21406213069 is 96031260412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18115814025 + 3290399044 = 134595^2 + 57362^2 .

It is a cyclic number.

It is not a de Polignac number, because 21406213069 - 2²⁹ = 20869342157 is a prime.

It is a super-2 number, since 2×21406213069² (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 (21406213019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10703106534 + 10703106535.

It is an arithmetic number, because the mean of its divisors is an integer number (10703106535).

Almost surely, 2^21406213069 is an apocalyptic number.

It is an amenable number.

21406213069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21406213069 is an equidigital number, since it uses as much as digits as its factorization.

21406213069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 34.

The spelling of 21406213069 in words is "twenty-one billion, four hundred six million, two hundred thirteen thousand, sixty-nine".