21779331 has 16 divisors (see below), whose sum is σ = 33644544. Its totient is φ = 12273984.

The previous prime is 21779311. The next prime is 21779333. The reversal of 21779331 is 13397712.

It is a happy number.

It is not a de Polignac number, because 21779331 - 2¹⁴ = 21762947 is a prime.

It is a super-2 number, since 2×21779331² = 948678517615122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21779292 and 21779301.

It is not an unprimeable number, because it can be changed into a prime (21779333) 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 15 ways as a sum of consecutive naturals, for example, 5571 + ... + 8636.

It is an arithmetic number, because the mean of its divisors is an integer number (2102784).

Almost surely, 2^21779331 is an apocalyptic number.

21779331 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21779331 is a deficient number, since it is larger than the sum of its proper divisors (11865213).

21779331 is a wasteful number, since it uses less digits than its factorization.

21779331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14290.

The product of its digits is 7938, while the sum is 33.

The square root of 21779331 is about 4666.8330803662. The cubic root of 21779331 is about 279.2639297931.

The spelling of 21779331 in words is "twenty-one million, seven hundred seventy-nine thousand, three hundred thirty-one".