21840667 has 2 divisors, whose sum is σ = 21840668. Its totient is φ = 21840666.

The previous prime is 21840641. The next prime is 21840673. The reversal of 21840667 is 76604812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21840667 is a prime.

It is not a weakly prime, because it can be changed into another prime (21840607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10920333 + 10920334.

It is an arithmetic number, because the mean of its divisors is an integer number (10920334).

Almost surely, 2^21840667 is an apocalyptic number.

21840667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21840667 is an equidigital number, since it uses as much as digits as its factorization.

21840667 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 21840667 is about 4673.3999400864. The cubic root of 21840667 is about 279.5258429152.

The spelling of 21840667 in words is "twenty-one million, eight hundred forty thousand, six hundred sixty-seven".