21680474 has 16 divisors (see below), whose sum is σ = 34523496. Its totient is φ = 10176000.

The previous prime is 21680473. The next prime is 21680479. The reversal of 21680474 is 47408612.

It can be written as a sum of positive squares in 4 ways, for example, as 21669025 + 11449 = 4655^2 + 107^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21680474.

It is not an unprimeable number, because it can be changed into a prime (21680473) 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, 19904 + ... + 20964.

Almost surely, 2^21680474 is an apocalyptic number.

21680474 is a deficient number, since it is larger than the sum of its proper divisors (12843022).

21680474 is a wasteful number, since it uses less digits than its factorization.

21680474 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1681.

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 21680474 is about 4656.2295905593. The cubic root of 21680474 is about 278.8407599247.

The spelling of 21680474 in words is "twenty-one million, six hundred eighty thousand, four hundred seventy-four".