21506234 has 8 divisors (see below), whose sum is σ = 32868180. Its totient is φ = 10550176.

The previous prime is 21506209. The next prime is 21506257. The reversal of 21506234 is 43260512.

It can be written as a sum of positive squares in 2 ways, for example, as 19936225 + 1570009 = 4465^2 + 1253^2 .

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

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, 101339 + ... + 101550.

Almost surely, 2^21506234 is an apocalyptic number.

21506234 is a deficient number, since it is larger than the sum of its proper divisors (11361946).

21506234 is a wasteful number, since it uses less digits than its factorization.

21506234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202944.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21506234 is about 4637.4814285342. The cubic root of 21506234 is about 278.0917610237.

Adding to 21506234 its reverse (43260512), we get a palindrome (64766746).

The spelling of 21506234 in words is "twenty-one million, five hundred six thousand, two hundred thirty-four".