21506346 has 12 divisors (see below), whose sum is σ = 46597122. Its totient is φ = 7168776.

The previous prime is 21506341. The next prime is 21506369. The reversal of 21506346 is 64360512.

21506346 is a `hidden beast` number, since 21 + 5 + 0 + 634 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21261321 + 245025 = 4611^2 + 495^2 .

It is not an unprimeable number, because it can be changed into a prime (21506341) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 597381 + ... + 597416.

Almost surely, 2^21506346 is an apocalyptic number.

21506346 is an abundant number, since it is smaller than the sum of its proper divisors (25090776).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21506346 is a wasteful number, since it uses less digits than its factorization.

21506346 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1194805 (or 1194802 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 21506346 is about 4637.4935040386. The cubic root of 21506346 is about 278.0922437709.

Adding to 21506346 its reverse (64360512), we get a palindrome (85866858).

The spelling of 21506346 in words is "twenty-one million, five hundred six thousand, three hundred forty-six".