21361617 has 16 divisors (see below), whose sum is σ = 32503680. Its totient is φ = 13855536.

The previous prime is 21361609. The next prime is 21361619. The reversal of 21361617 is 71616312.

It is not a de Polignac number, because 21361617 - 2³ = 21361609 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 (21361619) 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, 9693 + ... + 11690.

It is an arithmetic number, because the mean of its divisors is an integer number (2031480).

Almost surely, 2^21361617 is an apocalyptic number.

21361617 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21361617 is a deficient number, since it is larger than the sum of its proper divisors (11142063).

21361617 is a wasteful number, since it uses less digits than its factorization.

21361617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21429 (or 21423 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 21361617 is about 4621.8629360897. The cubic root of 21361617 is about 277.4670231084.

Adding to 21361617 its reverse (71616312), we get a palindrome (92977929).

It can be divided in two parts, 21 and 361617, that multiplied together give a palindrome (7593957).

The spelling of 21361617 in words is "twenty-one million, three hundred sixty-one thousand, six hundred seventeen".