21799779 has 8 divisors (see below), whose sum is σ = 29094912. Its totient is φ = 14518920.

The previous prime is 21799777. The next prime is 21799781. The reversal of 21799779 is 97799712.

It is an interprime number because it is at equal distance from previous prime (21799777) and next prime (21799781).

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

It is not a de Polignac number, because 21799779 - 2¹ = 21799777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21799777) 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, 742 + ... + 6644.

It is an arithmetic number, because the mean of its divisors is an integer number (3636864).

Almost surely, 2^21799779 is an apocalyptic number.

21799779 is a deficient number, since it is larger than the sum of its proper divisors (7295133).

21799779 is a wasteful number, since it uses less digits than its factorization.

21799779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7137.

The product of its digits is 500094, while the sum is 51.

The square root of 21799779 is about 4669.0233454118. The cubic root of 21799779 is about 279.3513001331.

It can be divided in two parts, 21799 and 779, that added together give a triangular number (22578 = T₂₁₂).

The spelling of 21799779 in words is "twenty-one million, seven hundred ninety-nine thousand, seven hundred seventy-nine".