21012030 has 48 divisors (see below), whose sum is σ = 58836960. Its totient is φ = 5171904.

The previous prime is 21011981. The next prime is 21012053. The reversal of 21012030 is 3021012.

It is a happy number.

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

It is a Curzon number.

It is a congruent number.

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, 7810 + ... + 10149.

It is an arithmetic number, because the mean of its divisors is an integer number (1225770).

Almost surely, 2^21012030 is an apocalyptic number.

21012030 is an abundant number, since it is smaller than the sum of its proper divisors (37824930).

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

21012030 is a wasteful number, since it uses less digits than its factorization.

21012030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17985 (or 17982 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21012030 is about 4583.8880876391. Note that the first 3 decimals coincide. The cubic root of 21012030 is about 275.9450898955.

Adding to 21012030 its reverse (3021012), we get a palindrome (24033042).

The spelling of 21012030 in words is "twenty-one million, twelve thousand, thirty".