21612031 has 8 divisors (see below), whose sum is σ = 24727680. Its totient is φ = 18503448.

The previous prime is 21612023. The next prime is 21612037. The reversal of 21612031 is 13021612.

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 21612031 - 2³ = 21612023 is a prime.

It is a super-2 number, since 2×21612031² = 934159767889922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21611996 and 21612014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21612037) 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, 10380 + ... + 12286.

It is an arithmetic number, because the mean of its divisors is an integer number (3090960).

Almost surely, 2^21612031 is an apocalyptic number.

21612031 is a deficient number, since it is larger than the sum of its proper divisors (3115649).

21612031 is a wasteful number, since it uses less digits than its factorization.

21612031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3533.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21612031 is about 4648.8741647844. The cubic root of 21612031 is about 278.5470268598.

Adding to 21612031 its reverse (13021612), we get a palindrome (34633643).

The spelling of 21612031 in words is "twenty-one million, six hundred twelve thousand, thirty-one".