21290370 has 16 divisors (see below), whose sum is σ = 51096960. Its totient is φ = 5677424.

The previous prime is 21290351. The next prime is 21290371. The reversal of 21290370 is 7309212.

It is a self number, because there is not a number n which added to its sum of digits gives 21290370.

It is not an unprimeable number, because it can be changed into a prime (21290371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 354810 + ... + 354869.

It is an arithmetic number, because the mean of its divisors is an integer number (3193560).

Almost surely, 2^21290370 is an apocalyptic number.

21290370 is an abundant number, since it is smaller than the sum of its proper divisors (29806590).

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

21290370 is a wasteful number, since it uses less digits than its factorization.

21290370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 709689.

The product of its (nonzero) digits is 756, while the sum is 24.

The square root of 21290370 is about 4614.1488922660. The cubic root of 21290370 is about 277.1582026687.

Adding to 21290370 its reverse (7309212), we get a palindrome (28599582).

The spelling of 21290370 in words is "twenty-one million, two hundred ninety thousand, three hundred seventy".