1230000021 has 6 divisors (see below), whose sum is σ = 1776666710. Its totient is φ = 820000008.

The previous prime is 1229999999. The next prime is 1230000047. The reversal of 1230000021 is 1200000321.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 827195121 + 402804900 = 28761^2 + 20070^2 .

It is not a de Polignac number, because 1230000021 - 2⁷ = 1229999893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 136666669 = 1230000021 / (1 + 2 + 3 + 0 + 0 + 0 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1229999958 and 1230000012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1230000091) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 68333326 + ... + 68333343.

Almost surely, 2^1230000021 is an apocalyptic number.

It is an amenable number.

1230000021 is a deficient number, since it is larger than the sum of its proper divisors (546666689).

1230000021 is a wasteful number, since it uses less digits than its factorization.

1230000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136666675 (or 136666672 counting only the distinct ones).

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

The square root of 1230000021 is about 35071.3561328900. The cubic root of 1230000021 is about 1071.4412757884.

Adding to 1230000021 its reverse (1200000321), we get a palindrome (2430000342).

The spelling of 1230000021 in words is "one billion, two hundred thirty million, twenty-one", and thus it is an aban number.