21319779 has 8 divisors (see below), whose sum is σ = 30613072. Its totient is φ = 13119840.

The previous prime is 21319777. The next prime is 21319783. The reversal of 21319779 is 97791312.

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

It is not a de Polignac number, because 21319779 - 2¹ = 21319777 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39), and also a Moran number because the ratio is a prime number: 546661 = 21319779 / (2 + 1 + 3 + 1 + 9 + 7 + 7 + 9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21319777) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 273292 + ... + 273369.

It is an arithmetic number, because the mean of its divisors is an integer number (3826634).

Almost surely, 2^21319779 is an apocalyptic number.

21319779 is a deficient number, since it is larger than the sum of its proper divisors (9293293).

21319779 is a wasteful number, since it uses less digits than its factorization.

21319779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 546677.

The product of its digits is 23814, while the sum is 39.

The square root of 21319779 is about 4617.3346207525. The cubic root of 21319779 is about 277.2857594845.

The spelling of 21319779 in words is "twenty-one million, three hundred nineteen thousand, seven hundred seventy-nine".