21554131447 has 2 divisors, whose sum is σ = 21554131448. Its totient is φ = 21554131446.

The previous prime is 21554131433. The next prime is 21554131523. The reversal of 21554131447 is 74413145512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21554131447 - 2¹⁵ = 21554098679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21554137447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777065723 + 10777065724.

It is an arithmetic number, because the mean of its divisors is an integer number (10777065724).

Almost surely, 2^21554131447 is an apocalyptic number.

21554131447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554131447 is an equidigital number, since it uses as much as digits as its factorization.

21554131447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 67200, while the sum is 37.

Adding to 21554131447 its reverse (74413145512), we get a palindrome (95967276959).

The spelling of 21554131447 in words is "twenty-one billion, five hundred fifty-four million, one hundred thirty-one thousand, four hundred forty-seven".