21268765 has 16 divisors (see below), whose sum is σ = 29308032. Its totient is φ = 14514624.

The previous prime is 21268763. The next prime is 21268777. The reversal of 21268765 is 56786212.

21268765 = 186² + 187² + ... + 412².

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21268765 - 2¹ = 21268763 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21268763) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6607 + ... + 9283.

It is an arithmetic number, because the mean of its divisors is an integer number (1831752).

Almost surely, 2^21268765 is an apocalyptic number.

It is an amenable number.

21268765 is a deficient number, since it is larger than the sum of its proper divisors (8039267).

21268765 is a wasteful number, since it uses less digits than its factorization.

21268765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2916.

The product of its digits is 40320, while the sum is 37.

The square root of 21268765 is about 4611.8071295318. The cubic root of 21268765 is about 277.0644195857.

The spelling of 21268765 in words is "twenty-one million, two hundred sixty-eight thousand, seven hundred sixty-five".