21173005 has 16 divisors (see below), whose sum is σ = 29473920. Its totient is φ = 14300352.

The previous prime is 21172999. The next prime is 21173021. The reversal of 21173005 is 50037112.

It is a cyclic number.

It is not a de Polignac number, because 21173005 - 2³ = 21172997 is a prime.

It is a super-2 number, since 2×21173005² = 896592281460050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2170 + ... + 6859.

It is an arithmetic number, because the mean of its divisors is an integer number (1842120).

Almost surely, 2^21173005 is an apocalyptic number.

It is an amenable number.

21173005 is a deficient number, since it is larger than the sum of its proper divisors (8300915).

21173005 is an equidigital number, since it uses as much as digits as its factorization.

21173005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9108.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21173005 is about 4601.4133698245. The cubic root of 21173005 is about 276.6479778024.

The spelling of 21173005 in words is "twenty-one million, one hundred seventy-three thousand, five".