21406370 has 8 divisors (see below), whose sum is σ = 38531484. Its totient is φ = 8562544.

The previous prime is 21406367. The next prime is 21406391. The reversal of 21406370 is 7360412.

It can be written as a sum of positive squares in 2 ways, for example, as 21169201 + 237169 = 4601^2 + 487^2 .

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1070309 + ... + 1070328.

Almost surely, 2^21406370 is an apocalyptic number.

21406370 is a deficient number, since it is larger than the sum of its proper divisors (17125114).

21406370 is a wasteful number, since it uses less digits than its factorization.

21406370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2140644.

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 21406370 is about 4626.7018490497. The cubic root of 21406370 is about 277.6606542076.

Adding to 21406370 its reverse (7360412), we get a palindrome (28766782).

The spelling of 21406370 in words is "twenty-one million, four hundred six thousand, three hundred seventy".