21090370 has 64 divisors (see below), whose sum is σ = 47278080. Its totient is φ = 6607872.

The previous prime is 21090367. The next prime is 21090371. The reversal of 21090370 is 7309012.

It is not an unprimeable number, because it can be changed into a prime (21090371) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43791 + ... + 44269.

It is an arithmetic number, because the mean of its divisors is an integer number (738720).

Almost surely, 2^21090370 is an apocalyptic number.

21090370 is an abundant number, since it is smaller than the sum of its proper divisors (26187710).

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

21090370 is a wasteful number, since it uses less digits than its factorization.

21090370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547.

The product of its (nonzero) digits is 378, while the sum is 22.

The square root of 21090370 is about 4592.4252851843. The cubic root of 21090370 is about 276.2876036524.

Adding to 21090370 its reverse (7309012), we get a palindrome (28399382).

The spelling of 21090370 in words is "twenty-one million, ninety thousand, three hundred seventy".