21079942 has 16 divisors (see below), whose sum is σ = 34563312. Its totient is φ = 9583200.

The previous prime is 21079931. The next prime is 21079979. The reversal of 21079942 is 24997012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21079898 and 21079907.

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, 4309 + ... + 7792.

It is an arithmetic number, because the mean of its divisors is an integer number (2160207).

Almost surely, 2^21079942 is an apocalyptic number.

21079942 is a deficient number, since it is larger than the sum of its proper divisors (13483370).

21079942 is a wasteful number, since it uses less digits than its factorization.

21079942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12183.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21079942 is about 4591.2897969960. The cubic root of 21079942 is about 276.2420599262.

The spelling of 21079942 in words is "twenty-one million, seventy-nine thousand, nine hundred forty-two".