21077760 has 144 divisors (see below), whose sum is σ = 73584000. Its totient is φ = 5099520.

The previous prime is 21077759. The next prime is 21077779. The reversal of 21077760 is 6777012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

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, 41991 + ... + 42489.

It is an arithmetic number, because the mean of its divisors is an integer number (511000).

Almost surely, 2^21077760 is an apocalyptic number.

21077760 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 21077760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36792000).

21077760 is an abundant number, since it is smaller than the sum of its proper divisors (52506240).

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

21077760 is a wasteful number, since it uses less digits than its factorization.

21077760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 534 (or 520 counting only the distinct ones).

The product of its (nonzero) digits is 4116, while the sum is 30.

The square root of 21077760 is about 4591.0521669874. The cubic root of 21077760 is about 276.2325282590.

The spelling of 21077760 in words is "twenty-one million, seventy-seven thousand, seven hundred sixty".