21423779 has 8 divisors (see below), whose sum is σ = 23867760. Its totient is φ = 19093536.

The previous prime is 21423769. The next prime is 21423781. The reversal of 21423779 is 97732412.

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 21423779 - 2⁴ = 21423763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21423709) 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, 28037 + ... + 28790.

It is an arithmetic number, because the mean of its divisors is an integer number (2983470).

Almost surely, 2^21423779 is an apocalyptic number.

21423779 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21423779 is a deficient number, since it is larger than the sum of its proper divisors (2443981).

21423779 is a wasteful number, since it uses less digits than its factorization.

21423779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56869.

The product of its digits is 21168, while the sum is 35.

The square root of 21423779 is about 4628.5828284692. The cubic root of 21423779 is about 277.7359041533.

The spelling of 21423779 in words is "twenty-one million, four hundred twenty-three thousand, seven hundred seventy-nine".