21689156 has 6 divisors (see below), whose sum is σ = 37956030. Its totient is φ = 10844576.

The previous prime is 21689153. The next prime is 21689159. The reversal of 21689156 is 65198612.

It is an interprime number because it is at equal distance from previous prime (21689153) and next prime (21689159).

It can be written as a sum of positive squares in only one way, i.e., 11022400 + 10666756 = 3320^2 + 3266^2 .

It is not an unprimeable number, because it can be changed into a prime (21689153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2711141 + ... + 2711148.

It is an arithmetic number, because the mean of its divisors is an integer number (6326005).

Almost surely, 2^21689156 is an apocalyptic number.

It is an amenable number.

21689156 is a deficient number, since it is larger than the sum of its proper divisors (16266874).

21689156 is a wasteful number, since it uses less digits than its factorization.

21689156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5422293 (or 5422291 counting only the distinct ones).

The product of its digits is 25920, while the sum is 38.

The square root of 21689156 is about 4657.1617966311. The cubic root of 21689156 is about 278.8779757838.

The spelling of 21689156 in words is "twenty-one million, six hundred eighty-nine thousand, one hundred fifty-six".