21500651 has 2 divisors, whose sum is σ = 21500652. Its totient is φ = 21500650.

The previous prime is 21500641. The next prime is 21500671. The reversal of 21500651 is 15600512.

It is an a-pointer prime, because the next prime (21500671) can be obtained adding 21500651 to its sum of digits (20).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21500651 - 2⁶ = 21500587 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21500621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750325 + 10750326.

It is an arithmetic number, because the mean of its divisors is an integer number (10750326).

Almost surely, 2^21500651 is an apocalyptic number.

21500651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500651 is an equidigital number, since it uses as much as digits as its factorization.

21500651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 21500651 is about 4636.8794463518. The cubic root of 21500651 is about 278.0676948131.

The spelling of 21500651 in words is "twenty-one million, five hundred thousand, six hundred fifty-one".