21615002 has 4 divisors (see below), whose sum is σ = 32422506. Its totient is φ = 10807500.

The previous prime is 21615001. The next prime is 21615047. The reversal of 21615002 is 20051612.

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., 21335161 + 279841 = 4619^2 + 529^2 .

It is a super-2 number, since 2×21615002² = 934416622920008, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21615001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5403749 + ... + 5403752.

Almost surely, 2^21615002 is an apocalyptic number.

21615002 is a deficient number, since it is larger than the sum of its proper divisors (10807504).

21615002 is a wasteful number, since it uses less digits than its factorization.

21615002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10807503.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21615002 is about 4649.1936935344. The cubic root of 21615002 is about 278.5597902029.

Adding to 21615002 its reverse (20051612), we get a palindrome (41666614).

The spelling of 21615002 in words is "twenty-one million, six hundred fifteen thousand, two".