21506126 has 8 divisors (see below), whose sum is σ = 33299904. Its totient is φ = 10406160.

The previous prime is 21506101. The next prime is 21506131. The reversal of 21506126 is 62160512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 173375 + ... + 173498.

It is an arithmetic number, because the mean of its divisors is an integer number (4162488).

Almost surely, 2^21506126 is an apocalyptic number.

21506126 is a deficient number, since it is larger than the sum of its proper divisors (11793778).

21506126 is a wasteful number, since it uses less digits than its factorization.

21506126 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346906.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21506126 is about 4637.4697842681. The cubic root of 21506126 is about 278.0912955159.

Adding to 21506126 its reverse (62160512), we get a palindrome (83666638).

The spelling of 21506126 in words is "twenty-one million, five hundred six thousand, one hundred twenty-six".