21390674 has 8 divisors (see below), whose sum is σ = 32370300. Its totient is φ = 10600576.

The previous prime is 21390673. The next prime is 21390727. The reversal of 21390674 is 47609312.

21390674 = T₁₇₂ + T₁₇₃ + ... + T₅₁₀.

It can be written as a sum of positive squares in 2 ways, for example, as 21390625 + 49 = 4625^2 + 7^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21390674.

It is not an unprimeable number, because it can be changed into a prime (21390671) 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 3 ways as a sum of consecutive naturals, for example, 47099 + ... + 47550.

Almost surely, 2^21390674 is an apocalyptic number.

21390674 is a deficient number, since it is larger than the sum of its proper divisors (10979626).

21390674 is a wasteful number, since it uses less digits than its factorization.

21390674 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94764.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 21390674 is about 4625.0052972943. The cubic root of 21390674 is about 277.5927736771.

Adding to 21390674 its reverse (47609312), we get a palindrome (68999986).

The spelling of 21390674 in words is "twenty-one million, three hundred ninety thousand, six hundred seventy-four".