21356507 has 2 divisors, whose sum is σ = 21356508. Its totient is φ = 21356506.

The previous prime is 21356497. The next prime is 21356549. The reversal of 21356507 is 70565312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21356507 - 2¹⁰ = 21355483 is a prime.

It is a super-2 number, since 2×21356507² = 912200782482098, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21356507.

It is not a weakly prime, because it can be changed into another prime (21356567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10678253 + 10678254.

It is an arithmetic number, because the mean of its divisors is an integer number (10678254).

Almost surely, 2^21356507 is an apocalyptic number.

21356507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21356507 is an equidigital number, since it uses as much as digits as its factorization.

21356507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6300, while the sum is 29.

The square root of 21356507 is about 4621.3100956331. The cubic root of 21356507 is about 277.4448966691. Note that the first 3 decimals are identical.

The spelling of 21356507 in words is "twenty-one million, three hundred fifty-six thousand, five hundred seven".