21213400129 has 2 divisors, whose sum is σ = 21213400130. Its totient is φ = 21213400128.

The previous prime is 21213400111. The next prime is 21213400157. The reversal of 21213400129 is 92100431212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19119422529 + 2093977600 = 138273^2 + 45760^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213400129 - 2¹¹ = 21213398081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21213400189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606700064 + 10606700065.

It is an arithmetic number, because the mean of its divisors is an integer number (10606700065).

Almost surely, 2^21213400129 is an apocalyptic number.

It is an amenable number.

21213400129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213400129 is an equidigital number, since it uses as much as digits as its factorization.

21213400129 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The spelling of 21213400129 in words is "twenty-one billion, two hundred thirteen million, four hundred thousand, one hundred twenty-nine".