21020776 has 16 divisors (see below), whose sum is σ = 45044640. Its totient is φ = 9008880.

The previous prime is 21020761. The next prime is 21020777. The reversal of 21020776 is 67702012.

It is a self number, because there is not a number n which added to its sum of digits gives 21020776.

It is not an unprimeable number, because it can be changed into a prime (21020777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 187630 + ... + 187741.

It is an arithmetic number, because the mean of its divisors is an integer number (2815290).

Almost surely, 2^21020776 is an apocalyptic number.

It is an amenable number.

21020776 is an abundant number, since it is smaller than the sum of its proper divisors (24023864).

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

21020776 is a wasteful number, since it uses less digits than its factorization.

21020776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375384 (or 375380 counting only the distinct ones).

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 21020776 is about 4584.8419820098. The cubic root of 21020776 is about 275.9833708388.

Adding to 21020776 its reverse (67702012), we get a palindrome (88722788).

The spelling of 21020776 in words is "twenty-one million, twenty thousand, seven hundred seventy-six".