21774779 has 16 divisors (see below), whose sum is σ = 24864000. Its totient is φ = 18903456.

The previous prime is 21774769. The next prime is 21774787. The reversal of 21774779 is 97747712.

It is not a de Polignac number, because 21774779 - 2⁴ = 21774763 is a prime.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21774749) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48932 + ... + 49374.

It is an arithmetic number, because the mean of its divisors is an integer number (1554000).

Almost surely, 2^21774779 is an apocalyptic number.

21774779 is a deficient number, since it is larger than the sum of its proper divisors (3089221).

21774779 is a wasteful number, since it uses less digits than its factorization.

21774779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 674.

The product of its digits is 172872, while the sum is 44.

The square root of 21774779 is about 4666.3453579863. The cubic root of 21774779 is about 279.2444725383.

The spelling of 21774779 in words is "twenty-one million, seven hundred seventy-four thousand, seven hundred seventy-nine".