21779842 has 32 divisors (see below), whose sum is σ = 38404224. Its totient is φ = 9072000.

The previous prime is 21779837. The next prime is 21779851. The reversal of 21779842 is 24897712.

It is a junction number, because it is equal to n+sod(n) for n = 21779795 and 21779804.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 103117 + ... + 103327.

It is an arithmetic number, because the mean of its divisors is an integer number (1200132).

Almost surely, 2^21779842 is an apocalyptic number.

21779842 is a deficient number, since it is larger than the sum of its proper divisors (16624382).

21779842 is a wasteful number, since it uses less digits than its factorization.

21779842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394.

The product of its digits is 56448, while the sum is 40.

The square root of 21779842 is about 4666.8878280927. The cubic root of 21779842 is about 279.2661138632.

The spelling of 21779842 in words is "twenty-one million, seven hundred seventy-nine thousand, eight hundred forty-two".