21379858 has 16 divisors (see below), whose sum is σ = 33707520. Its totient is φ = 10157616.

The previous prime is 21379837. The next prime is 21379879. The reversal of 21379858 is 85897312.

It is an interprime number because it is at equal distance from previous prime (21379837) and next prime (21379879).

It is a Harshad number since it is a multiple of its sum of digits (43).

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, 178 + ... + 6541.

It is an arithmetic number, because the mean of its divisors is an integer number (2106720).

Almost surely, 2^21379858 is an apocalyptic number.

21379858 is a deficient number, since it is larger than the sum of its proper divisors (12327662).

21379858 is a wasteful number, since it uses less digits than its factorization.

21379858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6801.

The product of its digits is 120960, while the sum is 43.

The square root of 21379858 is about 4623.8358534879. The cubic root of 21379858 is about 277.5459783675.

The spelling of 21379858 in words is "twenty-one million, three hundred seventy-nine thousand, eight hundred fifty-eight".