21712545 has 12 divisors (see below), whose sum is σ = 37635156. Its totient is φ = 11580000.

The previous prime is 21712541. The next prime is 21712567. The reversal of 21712545 is 54521712.

It can be written as a sum of positive squares in 2 ways, for example, as 3359889 + 18352656 = 1833^2 + 4284^2 .

It is not a de Polignac number, because 21712545 - 2² = 21712541 is a prime.

It is a super-2 number, since 2×21712545² = 942869220754050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21712541) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 241206 + ... + 241295.

It is an arithmetic number, because the mean of its divisors is an integer number (3136263).

Almost surely, 2^21712545 is an apocalyptic number.

It is an amenable number.

21712545 is a deficient number, since it is larger than the sum of its proper divisors (15922611).

21712545 is a wasteful number, since it uses less digits than its factorization.

21712545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 482512 (or 482509 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 21712545 is about 4659.6721987711. The cubic root of 21712545 is about 278.9781845971.

The spelling of 21712545 in words is "twenty-one million, seven hundred twelve thousand, five hundred forty-five".