21002545 has 8 divisors (see below), whose sum is σ = 25522560. Its totient is φ = 16589040.

The previous prime is 21002539. The next prime is 21002549. The reversal of 21002545 is 54520012.

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

It is a de Polignac number, because none of the positive numbers 2^k-21002545 is a prime.

It is a super-2 number, since 2×21002545² = 882213792954050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21002549) 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, 26191 + ... + 26980.

It is an arithmetic number, because the mean of its divisors is an integer number (3190320).

Almost surely, 2^21002545 is an apocalyptic number.

It is an amenable number.

21002545 is a deficient number, since it is larger than the sum of its proper divisors (4520015).

21002545 is an equidigital number, since it uses as much as digits as its factorization.

21002545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53255.

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 21002545 is about 4582.8533688086. The cubic root of 21002545 is about 275.9035623657.

Adding to 21002545 its reverse (54520012), we get a palindrome (75522557).

The spelling of 21002545 in words is "twenty-one million, two thousand, five hundred forty-five".