21047766 has 16 divisors (see below), whose sum is σ = 42330288. Its totient is φ = 6976800.

The previous prime is 21047713. The next prime is 21047771. The reversal of 21047766 is 66774012.

It is a congruent number.

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, 8605 + ... + 10776.

It is an arithmetic number, because the mean of its divisors is an integer number (2645643).

Almost surely, 2^21047766 is an apocalyptic number.

21047766 is an abundant number, since it is smaller than the sum of its proper divisors (21282522).

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

21047766 is a wasteful number, since it uses less digits than its factorization.

21047766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19567.

The product of its (nonzero) digits is 14112, while the sum is 33.

The square root of 21047766 is about 4587.7844325992. The cubic root of 21047766 is about 276.1014382442.

It can be divided in two parts, 2104 and 7766, that added together give a triangular number (9870 = T₁₄₀).

The spelling of 21047766 in words is "twenty-one million, forty-seven thousand, seven hundred sixty-six".