21052706 has 4 divisors (see below), whose sum is σ = 31579062. Its totient is φ = 10526352.

The previous prime is 21052687. The next prime is 21052709. The reversal of 21052706 is 60725012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 15721225 + 5331481 = 3965^2 + 2309^2 .

It is not an unprimeable number, because it can be changed into a prime (21052709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5263175 + ... + 5263178.

Almost surely, 2^21052706 is an apocalyptic number.

21052706 is a deficient number, since it is larger than the sum of its proper divisors (10526356).

21052706 is a wasteful number, since it uses less digits than its factorization.

21052706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10526355.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21052706 is about 4588.3227872503. The cubic root of 21052706 is about 276.1230372809.

Adding to 21052706 its reverse (60725012), we get a palindrome (81777718).

The spelling of 21052706 in words is "twenty-one million, fifty-two thousand, seven hundred six".