21777389 has 8 divisors (see below), whose sum is σ = 22939200. Its totient is φ = 20633536.

The previous prime is 21777367. The next prime is 21777419. The reversal of 21777389 is 98377712.

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 21777389 - 2¹⁶ = 21711853 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21777359) 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, 1964 + ... + 6885.

It is an arithmetic number, because the mean of its divisors is an integer number (2867400).

Almost surely, 2^21777389 is an apocalyptic number.

It is an amenable number.

21777389 is a deficient number, since it is larger than the sum of its proper divisors (1161811).

21777389 is a wasteful number, since it uses less digits than its factorization.

21777389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8979.

The product of its digits is 148176, while the sum is 44.

The square root of 21777389 is about 4666.6250117189. The cubic root of 21777389 is about 279.2556291606.

The spelling of 21777389 in words is "twenty-one million, seven hundred seventy-seven thousand, three hundred eighty-nine".