21390194429 has 2 divisors, whose sum is σ = 21390194430. Its totient is φ = 21390194428.

The previous prime is 21390194417. The next prime is 21390194443. The reversal of 21390194429 is 92449109312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12681012100 + 8709182329 = 112610^2 + 93323^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21390194429 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21390194429.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21390194459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695097214 + 10695097215.

It is an arithmetic number, because the mean of its divisors is an integer number (10695097215).

Almost surely, 2^21390194429 is an apocalyptic number.

It is an amenable number.

21390194429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21390194429 is an equidigital number, since it uses as much as digits as its factorization.

21390194429 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 44.

The spelling of 21390194429 in words is "twenty-one billion, three hundred ninety million, one hundred ninety-four thousand, four hundred twenty-nine".