21206012507 has 2 divisors, whose sum is σ = 21206012508. Its totient is φ = 21206012506.

The previous prime is 21206012459. The next prime is 21206012561. The reversal of 21206012507 is 70521060212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21206012507 - 2²² = 21201818203 is a prime.

It is not a weakly prime, because it can be changed into another prime (21206012567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10603006253 + 10603006254.

It is an arithmetic number, because the mean of its divisors is an integer number (10603006254).

Almost surely, 2^21206012507 is an apocalyptic number.

21206012507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21206012507 is an equidigital number, since it uses as much as digits as its factorization.

21206012507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1680, while the sum is 26.

Adding to 21206012507 its reverse (70521060212), we get a palindrome (91727072719).

The spelling of 21206012507 in words is "twenty-one billion, two hundred six million, twelve thousand, five hundred seven".