21777960 has 64 divisors (see below), whose sum is σ = 65894400. Its totient is φ = 5757696.

The previous prime is 21777953. The next prime is 21777979. The reversal of 21777960 is 6977712.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14526 + ... + 15954.

It is an arithmetic number, because the mean of its divisors is an integer number (1029600).

Almost surely, 2^21777960 is an apocalyptic number.

21777960 is a gapful number since it is divisible by the number (20) 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 21777960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32947200).

21777960 is an abundant number, since it is smaller than the sum of its proper divisors (44116440).

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

21777960 is a wasteful number, since it uses less digits than its factorization.

21777960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1570 (or 1566 counting only the distinct ones).

The product of its (nonzero) digits is 37044, while the sum is 39.

The square root of 21777960 is about 4666.6861904354. The cubic root of 21777960 is about 279.2580698200.

The spelling of 21777960 in words is "twenty-one million, seven hundred seventy-seven thousand, nine hundred sixty".