21372547 has 8 divisors (see below), whose sum is σ = 25213952. Its totient is φ = 17728200.

The previous prime is 21372541. The next prime is 21372551. The reversal of 21372547 is 74527312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21372547 - 2³ = 21372539 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21372541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49029 + ... + 49462.

It is an arithmetic number, because the mean of its divisors is an integer number (3151744).

Almost surely, 2^21372547 is an apocalyptic number.

21372547 is a deficient number, since it is larger than the sum of its proper divisors (3841405).

21372547 is an equidigital number, since it uses as much as digits as its factorization.

21372547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98529.

The product of its digits is 11760, while the sum is 31.

The square root of 21372547 is about 4623.0452085179. The cubic root of 21372547 is about 277.5143384632.

Adding to 21372547 its reverse (74527312), we get a palindrome (95899859).

The spelling of 21372547 in words is "twenty-one million, three hundred seventy-two thousand, five hundred forty-seven".