21382779 has 8 divisors (see below), whose sum is σ = 31102272. Its totient is φ = 12959240.

The previous prime is 21382763. The next prime is 21382783. The reversal of 21382779 is 97728312.

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

It is a cyclic number.

It is not a de Polignac number, because 21382779 - 2⁴ = 21382763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21382759) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 323949 + ... + 324014.

It is an arithmetic number, because the mean of its divisors is an integer number (3887784).

Almost surely, 2^21382779 is an apocalyptic number.

21382779 is a deficient number, since it is larger than the sum of its proper divisors (9719493).

21382779 is a wasteful number, since it uses less digits than its factorization.

21382779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 647977.

The product of its digits is 42336, while the sum is 39.

The square root of 21382779 is about 4624.1517059889. The cubic root of 21382779 is about 277.5586175984.

The spelling of 21382779 in words is "twenty-one million, three hundred eighty-two thousand, seven hundred seventy-nine".