21372545 has 8 divisors (see below), whose sum is σ = 26193024. Its totient is φ = 16734064.

The previous prime is 21372541. The next prime is 21372551. The reversal of 21372545 is 54527312.

It is a happy number.

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 21372545 - 2² = 21372541 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21372541) 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, 45239 + ... + 45708.

It is an arithmetic number, because the mean of its divisors is an integer number (3274128).

Almost surely, 2^21372545 is an apocalyptic number.

It is an amenable number.

21372545 is a deficient number, since it is larger than the sum of its proper divisors (4820479).

21372545 is an equidigital number, since it uses as much as digits as its factorization.

21372545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90999.

The product of its digits is 8400, while the sum is 29.

The square root of 21372545 is about 4623.0449922102. The cubic root of 21372545 is about 277.5143298068.

Adding to 21372545 its reverse (54527312), we get a palindrome (75899857).

The spelling of 21372545 in words is "twenty-one million, three hundred seventy-two thousand, five hundred forty-five".