21355970 has 8 divisors (see below), whose sum is σ = 38440764. Its totient is φ = 8542384.

The previous prime is 21355969. The next prime is 21355987. The reversal of 21355970 is 7955312.

It can be written as a sum of positive squares in 2 ways, for example, as 19918369 + 1437601 = 4463^2 + 1199^2 .

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1067789 + ... + 1067808.

Almost surely, 2^21355970 is an apocalyptic number.

21355970 is a deficient number, since it is larger than the sum of its proper divisors (17084794).

21355970 is a wasteful number, since it uses less digits than its factorization.

21355970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2135604.

The product of its (nonzero) digits is 9450, while the sum is 32.

The square root of 21355970 is about 4621.2519948603. The cubic root of 21355970 is about 277.4425712396.

The spelling of 21355970 in words is "twenty-one million, three hundred fifty-five thousand, nine hundred seventy".