21400214821 has 2 divisors, whose sum is σ = 21400214822. Its totient is φ = 21400214820.

The previous prime is 21400214807. The next prime is 21400214837. The reversal of 21400214821 is 12841200412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14262330625 + 7137884196 = 119425^2 + 84486^2 .

It is a cyclic number.

It is not a de Polignac number, because 21400214821 - 2⁹ = 21400214309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21400211821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700107410 + 10700107411.

It is an arithmetic number, because the mean of its divisors is an integer number (10700107411).

Almost surely, 2^21400214821 is an apocalyptic number.

It is an amenable number.

21400214821 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400214821 is an equidigital number, since it uses as much as digits as its factorization.

21400214821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1024, while the sum is 25.

The spelling of 21400214821 in words is "twenty-one billion, four hundred million, two hundred fourteen thousand, eight hundred twenty-one".