21021145 has 8 divisors (see below), whose sum is σ = 25260480. Its totient is φ = 16793520.

The previous prime is 21021127. The next prime is 21021157. The reversal of 21021145 is 54112012.

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

It is not a de Polignac number, because 21021145 - 2⁹ = 21020633 is a prime.

It is a super-2 number, since 2×21021145² = 883777074222050, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1690 + ... + 6700.

It is an arithmetic number, because the mean of its divisors is an integer number (3157560).

Almost surely, 2^21021145 is an apocalyptic number.

It is an amenable number.

21021145 is a deficient number, since it is larger than the sum of its proper divisors (4239335).

21021145 is an equidigital number, since it uses as much as digits as its factorization.

21021145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5855.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21021145 is about 4584.8822231329. The cubic root of 21021145 is about 275.9849857057.

Adding to 21021145 its reverse (54112012), we get a palindrome (75133157).

The spelling of 21021145 in words is "twenty-one million, twenty-one thousand, one hundred forty-five".