21053810 has 8 divisors (see below), whose sum is σ = 37896876. Its totient is φ = 8421520.

The previous prime is 21053783. The next prime is 21053831. The reversal of 21053810 is 1835012.

It can be written as a sum of positive squares in 2 ways, for example, as 20187049 + 866761 = 4493^2 + 931^2 .

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

It is a super-2 number, since 2×21053810² = 886525831032200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1052681 + ... + 1052700.

Almost surely, 2^21053810 is an apocalyptic number.

21053810 is a deficient number, since it is larger than the sum of its proper divisors (16843066).

21053810 is a wasteful number, since it uses less digits than its factorization.

21053810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2105388.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21053810 is about 4588.4430910713. The cubic root of 21053810 is about 276.1278638102.

Adding to 21053810 its reverse (1835012), we get a palindrome (22888822).

The spelling of 21053810 in words is "twenty-one million, fifty-three thousand, eight hundred ten".