21766331 has 4 divisors (see below), whose sum is σ = 21788832. Its totient is φ = 21743832.

The previous prime is 21766321. The next prime is 21766351. The reversal of 21766331 is 13366712.

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

It is a cyclic number.

It is not a de Polignac number, because 21766331 - 2¹⁰ = 21765307 is a prime.

It is a super-2 number, since 2×21766331² = 947546330403122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21766294 and 21766303.

It is not an unprimeable number, because it can be changed into a prime (21766301) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 9731 + ... + 11756.

It is an arithmetic number, because the mean of its divisors is an integer number (5447208).

Almost surely, 2^21766331 is an apocalyptic number.

21766331 is a deficient number, since it is larger than the sum of its proper divisors (22501).

21766331 is a wasteful number, since it uses less digits than its factorization.

21766331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22500.

The product of its digits is 4536, while the sum is 29.

The square root of 21766331 is about 4665.4400649885. The cubic root of 21766331 is about 279.2083548743.

The spelling of 21766331 in words is "twenty-one million, seven hundred sixty-six thousand, three hundred thirty-one".