21477760 has 64 divisors (see below), whose sum is σ = 52791120. Its totient is φ = 8349696.

The previous prime is 21477739. The next prime is 21477763. The reversal of 21477760 is 6777412.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×21477760² = 922588349235200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21477763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23227 + ... + 24133.

Almost surely, 2^21477760 is an apocalyptic number.

21477760 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 21477760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26395560).

21477760 is an abundant number, since it is smaller than the sum of its proper divisors (31313360).

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

21477760 is an equidigital number, since it uses as much as digits as its factorization.

21477760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 963 (or 951 counting only the distinct ones).

The product of its (nonzero) digits is 16464, while the sum is 34.

The square root of 21477760 is about 4634.4104263649. The cubic root of 21477760 is about 277.9689767496.

It can be divided in two parts, 21 and 477760, that multiplied together give a triangular number (10032960 = T₄₄₇₉).

The spelling of 21477760 in words is "twenty-one million, four hundred seventy-seven thousand, seven hundred sixty".