21001145 has 16 divisors (see below), whose sum is σ = 27613440. Its totient is φ = 15206400.

The previous prime is 21001121. The next prime is 21001153. The reversal of 21001145 is 54110012.

It is not a de Polignac number, because 21001145 - 2⁶ = 21001081 is a prime.

It is a super-2 number, since 2×21001145² = 882096182622050, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14201 + ... + 15609.

It is an arithmetic number, because the mean of its divisors is an integer number (1725840).

Almost surely, 2^21001145 is an apocalyptic number.

It is an amenable number.

21001145 is a deficient number, since it is larger than the sum of its proper divisors (6612295).

21001145 is a wasteful number, since it uses less digits than its factorization.

21001145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21001145 is about 4582.7006229951. The cubic root of 21001145 is about 275.8974317822.

Adding to 21001145 its reverse (54110012), we get a palindrome (75111157).

The spelling of 21001145 in words is "twenty-one million, one thousand, one hundred forty-five".