21264204551 has 2 divisors, whose sum is σ = 21264204552. Its totient is φ = 21264204550.

The previous prime is 21264204539. The next prime is 21264204553. The reversal of 21264204551 is 15540246212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21264204551 - 2¹⁸ = 21263942407 is a prime.

It is a super-2 number, since 2×21264204551² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 21264204553, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21264204553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632102275 + 10632102276.

It is an arithmetic number, because the mean of its divisors is an integer number (10632102276).

Almost surely, 2^21264204551 is an apocalyptic number.

21264204551 is a deficient number, since it is larger than the sum of its proper divisors (1).

21264204551 is an equidigital number, since it uses as much as digits as its factorization.

21264204551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19200, while the sum is 32.

The spelling of 21264204551 in words is "twenty-one billion, two hundred sixty-four million, two hundred four thousand, five hundred fifty-one".