21036810 has 16 divisors (see below), whose sum is σ = 50488416. Its totient is φ = 5609808.

The previous prime is 21036809. The next prime is 21036811. The reversal of 21036810 is 1863012.

It is an interprime number because it is at equal distance from previous prime (21036809) and next prime (21036811).

It is a super-2 number, since 2×21036810² = 885094749952200, which contains 22 as substring.

It is a zygodrome in base 4.

It is not an unprimeable number, because it can be changed into a prime (21036811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 350584 + ... + 350643.

It is an arithmetic number, because the mean of its divisors is an integer number (3155526).

Almost surely, 2^21036810 is an apocalyptic number.

21036810 is an abundant number, since it is smaller than the sum of its proper divisors (29451606).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21036810 is a wasteful number, since it uses less digits than its factorization.

21036810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701237.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21036810 is about 4586.5902367663. The cubic root of 21036810 is about 276.0535235412.

Adding to 21036810 its reverse (1863012), we get a palindrome (22899822).

The spelling of 21036810 in words is "twenty-one million, thirty-six thousand, eight hundred ten".