21553351511 has 2 divisors, whose sum is σ = 21553351512. Its totient is φ = 21553351510.

The previous prime is 21553351507. The next prime is 21553351513. The reversal of 21553351511 is 11515335512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21553351511 - 2² = 21553351507 is a prime.

It is a super-2 number, since 2×21553351511² (a number of 21 digits) contains 22 as substring.

Together with 21553351513, 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 (21553351513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776675755 + 10776675756.

It is an arithmetic number, because the mean of its divisors is an integer number (10776675756).

Almost surely, 2^21553351511 is an apocalyptic number.

21553351511 is a deficient number, since it is larger than the sum of its proper divisors (1).

21553351511 is an equidigital number, since it uses as much as digits as its factorization.

21553351511 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11250, while the sum is 32.

The spelling of 21553351511 in words is "twenty-one billion, five hundred fifty-three million, three hundred fifty-one thousand, five hundred eleven".