21049005 has 16 divisors (see below), whose sum is σ = 33888960. Its totient is φ = 11155968.

The previous prime is 21049001. The next prime is 21049019. The reversal of 21049005 is 50094012.

It is not a de Polignac number, because 21049005 - 2² = 21049001 is a prime.

It is a super-2 number, since 2×21049005² = 886121222980050, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21049001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1860 + ... + 6749.

It is an arithmetic number, because the mean of its divisors is an integer number (2118060).

Almost surely, 2^21049005 is an apocalyptic number.

It is an amenable number.

21049005 is a deficient number, since it is larger than the sum of its proper divisors (12839955).

21049005 is a wasteful number, since it uses less digits than its factorization.

21049005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8780.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 21049005 is about 4587.9194631118. The cubic root of 21049005 is about 276.1068558100.

The spelling of 21049005 in words is "twenty-one million, forty-nine thousand, five".