21201930 has 24 divisors (see below), whose sum is σ = 55125252. Its totient is φ = 5653824.

The previous prime is 21201919. The next prime is 21201931. The reversal of 21201930 is 3910212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19740249 + 1461681 = 4443^2 + 1209^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21201931) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 117699 + ... + 117878.

Almost surely, 2^21201930 is an apocalyptic number.

21201930 is an abundant number, since it is smaller than the sum of its proper divisors (33923322).

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

21201930 is a wasteful number, since it uses less digits than its factorization.

21201930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235590 (or 235587 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21201930 is about 4604.5553531259. Note that the first 3 decimals coincide. The cubic root of 21201930 is about 276.7738991756.

The spelling of 21201930 in words is "twenty-one million, two hundred one thousand, nine hundred thirty".