21405667 has 2 divisors, whose sum is σ = 21405668. Its totient is φ = 21405666.

The previous prime is 21405661. The next prime is 21405673. The reversal of 21405667 is 76650412.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (21405661) and next prime (21405673).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21405667 is a prime.

It is not a weakly prime, because it can be changed into another prime (21405661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702833 + 10702834.

It is an arithmetic number, because the mean of its divisors is an integer number (10702834).

Almost surely, 2^21405667 is an apocalyptic number.

21405667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21405667 is an equidigital number, since it uses as much as digits as its factorization.

21405667 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 21405667 is about 4626.6258763812. The cubic root of 21405667 is about 277.6576146516.

The spelling of 21405667 in words is "twenty-one million, four hundred five thousand, six hundred sixty-seven".