21779942 has 8 divisors (see below), whose sum is σ = 34090416. Its totient is φ = 10416472.

The previous prime is 21779917. The next prime is 21779971. The reversal of 21779942 is 24997712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21779942.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 236693 + ... + 236784.

It is an arithmetic number, because the mean of its divisors is an integer number (4261302).

Almost surely, 2^21779942 is an apocalyptic number.

21779942 is a deficient number, since it is larger than the sum of its proper divisors (12310474).

21779942 is a wasteful number, since it uses less digits than its factorization.

21779942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473502.

The product of its digits is 63504, while the sum is 41.

The square root of 21779942 is about 4666.8985418584. The cubic root of 21779942 is about 279.2665412701.

The spelling of 21779942 in words is "twenty-one million, seven hundred seventy-nine thousand, nine hundred forty-two".