21002893 has 6 divisors (see below), whose sum is σ = 21409514. Its totient is φ = 20603856.

The previous prime is 21002881. The next prime is 21002897. The reversal of 21002893 is 39820012.

It can be written as a sum of positive squares in 3 ways, for example, as 13089924 + 7912969 = 3618^2 + 2813^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21002893 is a prime.

It is a super-2 number, since 2×21002893² = 882243028738898, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002897) 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 5 ways as a sum of consecutive naturals, for example, 930 + ... + 6547.

Almost surely, 2^21002893 is an apocalyptic number.

It is an amenable number.

21002893 is a deficient number, since it is larger than the sum of its proper divisors (406621).

21002893 is an frugal number, since it uses more digits than its factorization.

21002893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7583 (or 7530 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21002893 is about 4582.8913362636. The cubic root of 21002893 is about 275.9050862114.

The spelling of 21002893 in words is "twenty-one million, two thousand, eight hundred ninety-three".