21390794 has 16 divisors (see below), whose sum is σ = 34360200. Its totient is φ = 9951744.

The previous prime is 21390793. The next prime is 21390797. The reversal of 21390794 is 49709312.

It can be written as a sum of positive squares in 4 ways, for example, as 16703569 + 4687225 = 4087^2 + 2165^2 .

It is a super-3 number, since 3×21390794³ (a number of 23 digits) contains 333 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21390791) 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, 509 + ... + 6560.

Almost surely, 2^21390794 is an apocalyptic number.

21390794 is a deficient number, since it is larger than the sum of its proper divisors (12969406).

21390794 is a wasteful number, since it uses less digits than its factorization.

21390794 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7177.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 21390794 is about 4625.0182702342. The cubic root of 21390794 is about 277.5932927673.

The spelling of 21390794 in words is "twenty-one million, three hundred ninety thousand, seven hundred ninety-four".