21002474 has 4 divisors (see below), whose sum is σ = 31503714. Its totient is φ = 10501236.

The previous prime is 21002461. The next prime is 21002477. The reversal of 21002474 is 47420012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20205025 + 797449 = 4495^2 + 893^2 .

It is a super-2 number, since 2×21002474² = 882207828241352, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21002477) 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 as a sum of consecutive naturals, namely, 5250617 + ... + 5250620.

Almost surely, 2^21002474 is an apocalyptic number.

21002474 is a deficient number, since it is larger than the sum of its proper divisors (10501240).

21002474 is a wasteful number, since it uses less digits than its factorization.

21002474 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10501239.

The product of its (nonzero) digits is 448, while the sum is 20.

The square root of 21002474 is about 4582.8456225363. The cubic root of 21002474 is about 275.9032514641.

Adding to 21002474 its reverse (47420012), we get a palindrome (68422486).

The spelling of 21002474 in words is "twenty-one million, two thousand, four hundred seventy-four".