21372417 has 60 divisors (see below), whose sum is σ = 37444176. Its totient is φ = 12044160.

The previous prime is 21372413. The next prime is 21372427. The reversal of 21372417 is 71427312.

It is a happy number.

It is not a de Polignac number, because 21372417 - 2² = 21372413 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 (21372413) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 257458 + ... + 257540.

Almost surely, 2^21372417 is an apocalyptic number.

21372417 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21372417 is a deficient number, since it is larger than the sum of its proper divisors (16071759).

21372417 is a wasteful number, since it uses less digits than its factorization.

21372417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 114 counting only the distinct ones).

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

The square root of 21372417 is about 4623.0311484999. The cubic root of 21372417 is about 277.5137757953.

Adding to 21372417 its reverse (71427312), we get a palindrome (92799729).

It can be divided in two parts, 2137 and 2417, that added together give a palindrome (4554).

The spelling of 21372417 in words is "twenty-one million, three hundred seventy-two thousand, four hundred seventeen".