21166051 has 2 divisors, whose sum is σ = 21166052. Its totient is φ = 21166050.

The previous prime is 21166009. The next prime is 21166099. The reversal of 21166051 is 15066112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21166051 - 2⁷ = 21165923 is a prime.

It is not a weakly prime, because it can be changed into another prime (21166151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10583025 + 10583026.

It is an arithmetic number, because the mean of its divisors is an integer number (10583026).

Almost surely, 2^21166051 is an apocalyptic number.

21166051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21166051 is an equidigital number, since it uses as much as digits as its factorization.

21166051 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21166051 is about 4600.6576703771. The cubic root of 21166051 is about 276.6176873344.

The spelling of 21166051 in words is "twenty-one million, one hundred sixty-six thousand, fifty-one".