21779814 has 64 divisors (see below), whose sum is σ = 53568000. Its totient is φ = 5884704.

The previous prime is 21779809. The next prime is 21779837. The reversal of 21779814 is 41897712.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

Its product of digits (28224) is a multiple of the sum of its prime divisors (588).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 38824 + ... + 39380.

It is an arithmetic number, because the mean of its divisors is an integer number (837000).

Almost surely, 2^21779814 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21779814, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26784000).

21779814 is an abundant number, since it is smaller than the sum of its proper divisors (31788186).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21779814 is a wasteful number, since it uses less digits than its factorization.

21779814 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 602 (or 588 counting only the distinct ones).

The product of its digits is 28224, while the sum is 39.

The square root of 21779814 is about 4666.8848282339. The cubic root of 21779814 is about 279.2659941890.

The spelling of 21779814 in words is "twenty-one million, seven hundred seventy-nine thousand, eight hundred fourteen".