21405521107 has 2 divisors, whose sum is σ = 21405521108. Its totient is φ = 21405521106.

The previous prime is 21405521069. The next prime is 21405521171. The reversal of 21405521107 is 70112550412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21405521107 - 2¹¹ = 21405519059 is a prime.

It is not a weakly prime, because it can be changed into another prime (21405521507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702760553 + 10702760554.

It is an arithmetic number, because the mean of its divisors is an integer number (10702760554).

Almost surely, 2^21405521107 is an apocalyptic number.

21405521107 is a deficient number, since it is larger than the sum of its proper divisors (1).

21405521107 is an equidigital number, since it uses as much as digits as its factorization.

21405521107 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2800, while the sum is 28.

The spelling of 21405521107 in words is "twenty-one billion, four hundred five million, five hundred twenty-one thousand, one hundred seven".