21777492 has 48 divisors (see below), whose sum is σ = 57355200. Its totient is φ = 6370560.

The previous prime is 21777491. The next prime is 21777517. The reversal of 21777492 is 29477712.

It is a self number, because there is not a number n which added to its sum of digits gives 21777492.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21777491) 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, 984 + ... + 6672.

It is an arithmetic number, because the mean of its divisors is an integer number (1194900).

Almost surely, 2^21777492 is an apocalyptic number.

21777492 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21777492, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28677600).

21777492 is an abundant number, since it is smaller than the sum of its proper divisors (35577708).

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

21777492 is a wasteful number, since it uses less digits than its factorization.

21777492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5736 (or 5734 counting only the distinct ones).

The product of its digits is 49392, while the sum is 39.

The square root of 21777492 is about 4666.6360475186. The cubic root of 21777492 is about 279.2560694228.

It can be divided in two parts, 2177 and 7492, that added together give a palindrome (9669).

The spelling of 21777492 in words is "twenty-one million, seven hundred seventy-seven thousand, four hundred ninety-two".