21005074 has 4 divisors (see below), whose sum is σ = 31507614. Its totient is φ = 10502536.

The previous prime is 21005069. The next prime is 21005087. The reversal of 21005074 is 47050012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20748025 + 257049 = 4555^2 + 507^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5251267 + ... + 5251270.

Almost surely, 2^21005074 is an apocalyptic number.

21005074 is a deficient number, since it is larger than the sum of its proper divisors (10502540).

21005074 is a wasteful number, since it uses less digits than its factorization.

21005074 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10502539.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 21005074 is about 4583.1292803062. The cubic root of 21005074 is about 275.9146361365.

Adding to 21005074 its reverse (47050012), we get a palindrome (68055086).

The spelling of 21005074 in words is "twenty-one million, five thousand, seventy-four".