21077520 has 80 divisors (see below), whose sum is σ = 67471872. Its totient is φ = 5437440.

The previous prime is 21077477. The next prime is 21077527. The reversal of 21077520 is 2577012.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21077527) 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, 6024 + ... + 8856.

Almost surely, 2^21077520 is an apocalyptic number.

21077520 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 21077520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33735936).

21077520 is an abundant number, since it is smaller than the sum of its proper divisors (46394352).

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

21077520 is a wasteful number, since it uses less digits than its factorization.

21077520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2880 (or 2874 counting only the distinct ones).

The product of its (nonzero) digits is 980, while the sum is 24.

The square root of 21077520 is about 4591.0260291138. The cubic root of 21077520 is about 276.2314798228.

The spelling of 21077520 in words is "twenty-one million, seventy-seven thousand, five hundred twenty".