21065772 has 96 divisors (see below), whose sum is σ = 61415424. Its totient is φ = 5472000.

The previous prime is 21065767. The next prime is 21065777. The reversal of 21065772 is 27756012.

It is an interprime number because it is at equal distance from previous prime (21065767) and next prime (21065777).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065777) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 110197 + ... + 110387.

It is an arithmetic number, because the mean of its divisors is an integer number (639744).

Almost surely, 2^21065772 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21065772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30707712).

21065772 is an abundant number, since it is smaller than the sum of its proper divisors (40349652).

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

21065772 is a wasteful number, since it uses less digits than its factorization.

21065772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319 (or 317 counting only the distinct ones).

The product of its (nonzero) digits is 5880, while the sum is 30.

The square root of 21065772 is about 4589.7463982229. The cubic root of 21065772 is about 276.1801491392.

The spelling of 21065772 in words is "twenty-one million, sixty-five thousand, seven hundred seventy-two".