21900030 has 32 divisors (see below), whose sum is σ = 52683264. Its totient is φ = 5826336.

The previous prime is 21900019. The next prime is 21900031. The reversal of 21900030 is 3000912.

It is a super-2 number, since 2×21900030² = 959222628001800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21899982 and 21900009.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21900031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24247 + ... + 25133.

It is an arithmetic number, because the mean of its divisors is an integer number (1646352).

Almost surely, 2^21900030 is an apocalyptic number.

21900030 is an abundant number, since it is smaller than the sum of its proper divisors (30783234).

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

21900030 is a wasteful number, since it uses less digits than its factorization.

21900030 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1720.

The product of its (nonzero) digits is 54, while the sum is 15.

The square root of 21900030 is about 4679.7467880218. The cubic root of 21900030 is about 279.7788645155.

Adding to 21900030 its reverse (3000912), we get a palindrome (24900942).

The spelling of 21900030 in words is "twenty-one million, nine hundred thousand, thirty".