21403432553 has 2 divisors, whose sum is σ = 21403432554. Its totient is φ = 21403432552.

The previous prime is 21403432541. The next prime is 21403432573. The reversal of 21403432553 is 35523430412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16146022489 + 5257410064 = 127067^2 + 72508^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403432553 - 2¹² = 21403428457 is a prime.

It is not a weakly prime, because it can be changed into another prime (21403432573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701716276 + 10701716277.

It is an arithmetic number, because the mean of its divisors is an integer number (10701716277).

Almost surely, 2^21403432553 is an apocalyptic number.

It is an amenable number.

21403432553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21403432553 is an equidigital number, since it uses as much as digits as its factorization.

21403432553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43200, while the sum is 32.

Adding to 21403432553 its reverse (35523430412), we get a palindrome (56926862965).

The spelling of 21403432553 in words is "twenty-one billion, four hundred three million, four hundred thirty-two thousand, five hundred fifty-three".