210021021 has 24 divisors (see below), whose sum is σ = 347547200. Its totient is φ = 119719296.

The previous prime is 210020989. The next prime is 210021047. The reversal of 210021021 is 120120012.

It is not a de Polignac number, because 210021021 - 2⁵ = 210020989 is a prime.

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

210021021 is a modest number, since divided by 21021 gives 210 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 210020994 and 210021012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210021121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23430 + ... + 31128.

Almost surely, 2^210021021 is an apocalyptic number.

210021021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

210021021 is a deficient number, since it is larger than the sum of its proper divisors (137526179).

210021021 is a wasteful number, since it uses less digits than its factorization.

210021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8145 (or 8142 counting only the distinct ones).

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

The square root of 210021021 is about 14492.1020214460. The cubic root of 210021021 is about 594.4120275008.

Adding to 210021021 its reverse (120120012), we get a palindrome (330141033).

The spelling of 210021021 in words is "two hundred ten million, twenty-one thousand, twenty-one".