21617372 has 24 divisors (see below), whose sum is σ = 43451520. Its totient is φ = 9218160.

The previous prime is 21617341. The next prime is 21617377. The reversal of 21617372 is 27371612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21617377) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4079 + ... + 7737.

It is an arithmetic number, because the mean of its divisors is an integer number (1810480).

Almost surely, 2^21617372 is an apocalyptic number.

It is an amenable number.

21617372 is an abundant number, since it is smaller than the sum of its proper divisors (21834148).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21617372 is a wasteful number, since it uses less digits than its factorization.

21617372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3881 (or 3879 counting only the distinct ones).

The product of its digits is 3528, while the sum is 29.

The square root of 21617372 is about 4649.4485694542. The cubic root of 21617372 is about 278.5699708261.

Adding to 21617372 its reverse (27371612), we get a palindrome (48988984).

The spelling of 21617372 in words is "twenty-one million, six hundred seventeen thousand, three hundred seventy-two".