21689265 has 16 divisors (see below), whose sum is σ = 37372608. Its totient is φ = 10677696.

The previous prime is 21689257. The next prime is 21689273. The reversal of 21689265 is 56298612.

It is an interprime number because it is at equal distance from previous prime (21689257) and next prime (21689273).

It is not a de Polignac number, because 21689265 - 2³ = 21689257 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55419 + ... + 55808.

It is an arithmetic number, because the mean of its divisors is an integer number (2335788).

Almost surely, 2^21689265 is an apocalyptic number.

It is an amenable number.

21689265 is a deficient number, since it is larger than the sum of its proper divisors (15683343).

21689265 is a wasteful number, since it uses less digits than its factorization.

21689265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111248.

The product of its digits is 51840, while the sum is 39.

The square root of 21689265 is about 4657.1734990228. The cubic root of 21689265 is about 278.8784429550.

The spelling of 21689265 in words is "twenty-one million, six hundred eighty-nine thousand, two hundred sixty-five".