21371506 has 16 divisors (see below), whose sum is σ = 34645464. Its totient is φ = 9828864.

The previous prime is 21371489. The next prime is 21371509. The reversal of 21371506 is 60517312.

It can be written as a sum of positive squares in 4 ways, for example, as 10182481 + 11189025 = 3191^2 + 3345^2 .

It is not an unprimeable number, because it can be changed into a prime (21371509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6946 + ... + 9538.

Almost surely, 2^21371506 is an apocalyptic number.

21371506 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21371506 is a deficient number, since it is larger than the sum of its proper divisors (13273958).

21371506 is a wasteful number, since it uses less digits than its factorization.

21371506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2925.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21371506 is about 4622.9326190201. The cubic root of 21371506 is about 277.5098327279.

Adding to 21371506 its reverse (60517312), we get a palindrome (81888818).

The spelling of 21371506 in words is "twenty-one million, three hundred seventy-one thousand, five hundred six".