21051506 has 32 divisors (see below), whose sum is σ = 39312000. Its totient is φ = 8249472.

The previous prime is 21051493. The next prime is 21051523. The reversal of 21051506 is 60515012.

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, 6350 + ... + 9078.

It is an arithmetic number, because the mean of its divisors is an integer number (1228500).

Almost surely, 2^21051506 is an apocalyptic number.

21051506 is a deficient number, since it is larger than the sum of its proper divisors (18260494).

21051506 is a wasteful number, since it uses less digits than its factorization.

21051506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2786.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 21051506 is about 4588.1920186496. The cubic root of 21051506 is about 276.1177908621.

Adding to 21051506 its reverse (60515012), we get a palindrome (81566518).

It can be divided in two parts, 2 and 1051506, that multiplied together give a palindrome (2103012).

The spelling of 21051506 in words is "twenty-one million, fifty-one thousand, five hundred six".