21017772 has 24 divisors (see below), whose sum is σ = 54490800. Its totient is φ = 7005888.

The previous prime is 21017761. The next prime is 21017803. The reversal of 21017772 is 27771012.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 97197 + ... + 97412.

It is an arithmetic number, because the mean of its divisors is an integer number (2270450).

Almost surely, 2^21017772 is an apocalyptic number.

It is an amenable number.

21017772 is an abundant number, since it is smaller than the sum of its proper divisors (33473028).

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

21017772 is a wasteful number, since it uses less digits than its factorization.

21017772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194622 (or 194614 counting only the distinct ones).

The product of its (nonzero) digits is 1372, while the sum is 27.

The square root of 21017772 is about 4584.5143690472. The cubic root of 21017772 is about 275.9702236308.

Adding to 21017772 its reverse (27771012), we get a palindrome (48788784).

The spelling of 21017772 in words is "twenty-one million, seventeen thousand, seven hundred seventy-two".