21798030 has 16 divisors (see below), whose sum is σ = 52315344. Its totient is φ = 5812800.

The previous prime is 21798017. The next prime is 21798047. The reversal of 21798030 is 3089712.

It is a happy number.

It is a super-2 number, since 2×21798030² = 950308223761800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 726601 = 21798030 / (2 + 1 + 7 + 9 + 8 + 0 + 3 + 0).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 363271 + ... + 363330.

It is an arithmetic number, because the mean of its divisors is an integer number (3269709).

Almost surely, 2^21798030 is an apocalyptic number.

21798030 is an abundant number, since it is smaller than the sum of its proper divisors (30517314).

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

21798030 is a wasteful number, since it uses less digits than its factorization.

21798030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 726611.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21798030 is about 4668.8360433838. The cubic root of 21798030 is about 279.3438291324.

The spelling of 21798030 in words is "twenty-one million, seven hundred ninety-eight thousand, thirty".