21012210 has 48 divisors (see below), whose sum is σ = 56661696. Its totient is φ = 5602608.

The previous prime is 21012193. The next prime is 21012227. The reversal of 21012210 is 1221012.

It is an interprime number because it is at equal distance from previous prime (21012193) and next prime (21012227).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21012192 and 21012201.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1894 + ... + 6753.

It is an arithmetic number, because the mean of its divisors is an integer number (1180452).

Almost surely, 2^21012210 is an apocalyptic number.

21012210 is an abundant number, since it is smaller than the sum of its proper divisors (35649486).

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

21012210 is an equidigital number, since it uses as much as digits as its factorization.

21012210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8669 (or 8657 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21012210 is about 4583.9077215843. The cubic root of 21012210 is about 275.9458778564.

Adding to 21012210 its reverse (1221012), we get a palindrome (22233222).

The spelling of 21012210 in words is "twenty-one million, twelve thousand, two hundred ten".