21315779 has 8 divisors (see below), whose sum is σ = 22608672. Its totient is φ = 20053440.

The previous prime is 21315761. The next prime is 21315793. The reversal of 21315779 is 97751312.

It is a happy number.

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 21315779 - 2¹² = 21311683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21315709) 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, 6194 + ... + 8999.

It is an arithmetic number, because the mean of its divisors is an integer number (2826084).

Almost surely, 2^21315779 is an apocalyptic number.

21315779 is a deficient number, since it is larger than the sum of its proper divisors (1292893).

21315779 is a wasteful number, since it uses less digits than its factorization.

21315779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15277.

The product of its digits is 13230, while the sum is 35.

The square root of 21315779 is about 4616.9014501070. The cubic root of 21315779 is about 277.2684170219.

The spelling of 21315779 in words is "twenty-one million, three hundred fifteen thousand, seven hundred seventy-nine".