21705370 has 8 divisors (see below), whose sum is σ = 39069684. Its totient is φ = 8682144.

The previous prime is 21705367. The next prime is 21705371. The reversal of 21705370 is 7350712.

It can be written as a sum of positive squares in 2 ways, for example, as 21427641 + 277729 = 4629^2 + 527^2 .

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

It is a super-2 number, since 2×21705370² = 942246173673800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21705371) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1085259 + ... + 1085278.

Almost surely, 2^21705370 is an apocalyptic number.

21705370 is a deficient number, since it is larger than the sum of its proper divisors (17364314).

21705370 is a wasteful number, since it uses less digits than its factorization.

21705370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2170544.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 21705370 is about 4658.9022312128. The cubic root of 21705370 is about 278.9474513812.

The spelling of 21705370 in words is "twenty-one million, seven hundred five thousand, three hundred seventy".