21053889 has 6 divisors (see below), whose sum is σ = 30411186. Its totient is φ = 14035920.

The previous prime is 21053887. The next prime is 21053897. The reversal of 21053889 is 98835012.

It can be written as a sum of positive squares in only one way, i.e., 15800625 + 5253264 = 3975^2 + 2292^2 .

It is not a de Polignac number, because 21053889 - 2¹ = 21053887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21053887) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1169652 + ... + 1169669.

It is an arithmetic number, because the mean of its divisors is an integer number (5068531).

Almost surely, 2^21053889 is an apocalyptic number.

It is an amenable number.

21053889 is a deficient number, since it is larger than the sum of its proper divisors (9357297).

21053889 is a wasteful number, since it uses less digits than its factorization.

21053889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2339327 (or 2339324 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21053889 is about 4588.4516996477. The cubic root of 21053889 is about 276.1282091803.

The spelling of 21053889 in words is "twenty-one million, fifty-three thousand, eight hundred eighty-nine".