21379518553 has 2 divisors, whose sum is σ = 21379518554. Its totient is φ = 21379518552.

The previous prime is 21379518487. The next prime is 21379518557. The reversal of 21379518553 is 35581597312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20931434329 + 448084224 = 144677^2 + 21168^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21379518553 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21379518497 and 21379518506.

It is not a weakly prime, because it can be changed into another prime (21379518557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10689759276 + 10689759277.

It is an arithmetic number, because the mean of its divisors is an integer number (10689759277).

Almost surely, 2^21379518553 is an apocalyptic number.

It is an amenable number.

21379518553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21379518553 is an equidigital number, since it uses as much as digits as its factorization.

21379518553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1134000, while the sum is 49.

The spelling of 21379518553 in words is "twenty-one billion, three hundred seventy-nine million, five hundred eighteen thousand, five hundred fifty-three".