21517474 has 8 divisors (see below), whose sum is σ = 35210448. Its totient is φ = 9780660.

The previous prime is 21517471. The next prime is 21517499. The reversal of 21517474 is 47471512.

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

It is not an unprimeable number, because it can be changed into a prime (21517471) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 489012 + ... + 489055.

It is an arithmetic number, because the mean of its divisors is an integer number (4401306).

Almost surely, 2^21517474 is an apocalyptic number.

21517474 is a deficient number, since it is larger than the sum of its proper divisors (13692974).

21517474 is a wasteful number, since it uses less digits than its factorization.

21517474 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 978080.

The product of its digits is 7840, while the sum is 31.

The square root of 21517474 is about 4638.6931349250. The cubic root of 21517474 is about 278.1401998005.

Adding to 21517474 its reverse (47471512), we get a palindrome (68988986).

It can be divided in two parts, 215 and 17474, that added together give a square (17689 = 133²).

The spelling of 21517474 in words is "twenty-one million, five hundred seventeen thousand, four hundred seventy-four".