21124400551 has 2 divisors, whose sum is σ = 21124400552. Its totient is φ = 21124400550.

The previous prime is 21124400537. The next prime is 21124400579. The reversal of 21124400551 is 15500442112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21124400551 - 2²¹ = 21122303399 is a prime.

It is a super-4 number, since 4×21124400551⁴ (a number of 42 digits) contains 4444 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21124403551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562200275 + 10562200276.

It is an arithmetic number, because the mean of its divisors is an integer number (10562200276).

Almost surely, 2^21124400551 is an apocalyptic number.

21124400551 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124400551 is an equidigital number, since it uses as much as digits as its factorization.

21124400551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 21124400551 its reverse (15500442112), we get a palindrome (36624842663).

The spelling of 21124400551 in words is "twenty-one billion, one hundred twenty-four million, four hundred thousand, five hundred fifty-one".