21521212507 has 2 divisors, whose sum is σ = 21521212508. Its totient is φ = 21521212506.

The previous prime is 21521212501. The next prime is 21521212523. The reversal of 21521212507 is 70521212512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21521212507 - 2¹⁵ = 21521179739 is a prime.

It is not a weakly prime, because it can be changed into another prime (21521212501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10760606253 + 10760606254.

It is an arithmetic number, because the mean of its divisors is an integer number (10760606254).

Almost surely, 2^21521212507 is an apocalyptic number.

21521212507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21521212507 is an equidigital number, since it uses as much as digits as its factorization.

21521212507 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 21521212507 in words is "twenty-one billion, five hundred twenty-one million, two hundred twelve thousand, five hundred seven".