21821070 has 16 divisors (see below), whose sum is σ = 52370640. Its totient is φ = 5818944.

The previous prime is 21821039. The next prime is 21821071. The reversal of 21821070 is 7012812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21821071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 363655 + ... + 363714.

It is an arithmetic number, because the mean of its divisors is an integer number (3273165).

Almost surely, 2^21821070 is an apocalyptic number.

21821070 is an abundant number, since it is smaller than the sum of its proper divisors (30549570).

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

21821070 is a wasteful number, since it uses less digits than its factorization.

21821070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727379.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 21821070 is about 4671.3028161317. The cubic root of 21821070 is about 279.4422144079.

Adding to 21821070 its reverse (7012812), we get a palindrome (28833882).

The spelling of 21821070 in words is "twenty-one million, eight hundred twenty-one thousand, seventy".