21378560 has 80 divisors (see below), whose sum is σ = 58630176. Its totient is φ = 7323648.

The previous prime is 21378547. The next prime is 21378587. The reversal of 21378560 is 6587312.

It is a happy number.

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 (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17324 + ... + 18516.

Almost surely, 2^21378560 is an apocalyptic number.

21378560 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 21378560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29315088).

21378560 is an abundant number, since it is smaller than the sum of its proper divisors (37251616).

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

21378560 is an equidigital number, since it uses as much as digits as its factorization.

21378560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1223 (or 1207 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21378560 is about 4623.6954917036. The cubic root of 21378560 is about 277.5403615237.

The spelling of 21378560 in words is "twenty-one million, three hundred seventy-eight thousand, five hundred sixty".