21612473 has 6 divisors (see below), whose sum is σ = 21847086. Its totient is φ = 21380352.

The previous prime is 21612431. The next prime is 21612497. The reversal of 21612473 is 37421612.

It can be written as a sum of positive squares in 3 ways, for example, as 2226064 + 19386409 = 1492^2 + 4403^2 .

It is not a de Polignac number, because 21612473 - 2²² = 17418169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21612413) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8261 + ... + 10557.

It is an arithmetic number, because the mean of its divisors is an integer number (3641181).

Almost surely, 2^21612473 is an apocalyptic number.

It is an amenable number.

21612473 is a deficient number, since it is larger than the sum of its proper divisors (234613).

21612473 is an frugal number, since it uses more digits than its factorization.

With its predecessor (21612472) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (2491).

21612473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2491 (or 2394 counting only the distinct ones).

The product of its digits is 2016, while the sum is 26.

The square root of 21612473 is about 4648.9217029328. The cubic root of 21612473 is about 278.5489257550.

The spelling of 21612473 in words is "twenty-one million, six hundred twelve thousand, four hundred seventy-three".