21061266 has 16 divisors (see below), whose sum is σ = 44600544. Its totient is φ = 6607424.

The previous prime is 21061259. The next prime is 21061309. The reversal of 21061266 is 66216012.

It is an unprimeable number.

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, 103140 + ... + 103343.

It is an arithmetic number, because the mean of its divisors is an integer number (2787534).

Almost surely, 2^21061266 is an apocalyptic number.

21061266 is the 2903-rd centered pentagonal number.

21061266 is an abundant number, since it is smaller than the sum of its proper divisors (23539278).

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

21061266 is a wasteful number, since it uses less digits than its factorization.

21061266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206505.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21061266 is about 4589.2554951757. The cubic root of 21061266 is about 276.1604559533.

Adding to 21061266 its reverse (66216012), we get a palindrome (87277278).

The spelling of 21061266 in words is "twenty-one million, sixty-one thousand, two hundred sixty-six".