21020560 has 40 divisors (see below), whose sum is σ = 53318016. Its totient is φ = 7643520.

The previous prime is 21020543. The next prime is 21020581. The reversal of 21020560 is 6502012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is an unprimeable number.

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, 11064 + ... + 12823.

Almost surely, 2^21020560 is an apocalyptic number.

21020560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020560 is an abundant number, since it is smaller than the sum of its proper divisors (32297456).

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

21020560 is a wasteful number, since it uses less digits than its factorization.

21020560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23911 (or 23905 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21020560 is about 4584.8184260666. The cubic root of 21020560 is about 275.9824255420.

Adding to 21020560 its reverse (6502012), we get a palindrome (27522572).

The spelling of 21020560 in words is "twenty-one million, twenty thousand, five hundred sixty".