21734217 has 16 divisors (see below), whose sum is σ = 32642880. Its totient is φ = 14289696.

The previous prime is 21734213. The next prime is 21734261. The reversal of 21734217 is 71243712.

It is a happy number.

It is not a de Polignac number, because 21734217 - 2² = 21734213 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (21734213) 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, 3543 + ... + 7484.

It is an arithmetic number, because the mean of its divisors is an integer number (2040180).

Almost surely, 2^21734217 is an apocalyptic number.

21734217 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21734217 is a deficient number, since it is larger than the sum of its proper divisors (10908663).

21734217 is a wasteful number, since it uses less digits than its factorization.

21734217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11109 (or 11103 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21734217 is about 4661.9971042462. The cubic root of 21734217 is about 279.0709728102.

Adding to 21734217 its sum of digits (27), we get a square (21734244 = 4662²).

Adding to 21734217 its reverse (71243712), we get a palindrome (92977929).

The spelling of 21734217 in words is "twenty-one million, seven hundred thirty-four thousand, two hundred seventeen".