15217421 has 8 divisors (see below), whose sum is σ = 15924480. Its totient is φ = 14514192.

The previous prime is 15217417. The next prime is 15217427. The reversal of 15217421 is 12471251.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 15217421 - 2² = 15217417 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15217427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9935 + ... + 11363.

It is an arithmetic number, because the mean of its divisors is an integer number (1990560).

Almost surely, 2^15217421 is an apocalyptic number.

It is an amenable number.

15217421 is a deficient number, since it is larger than the sum of its proper divisors (707059).

15217421 is a wasteful number, since it uses less digits than its factorization.

15217421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1915.

The product of its digits is 560, while the sum is 23.

The square root of 15217421 is about 3900.9512942358. The cubic root of 15217421 is about 247.8070657345.

Adding to 15217421 its reverse (12471251), we get a palindrome (27688672).

The spelling of 15217421 in words is "fifteen million, two hundred seventeen thousand, four hundred twenty-one".