21042615 has 32 divisors (see below), whose sum is σ = 37253376. Its totient is φ = 10056960.

The previous prime is 21042601. The next prime is 21042629. The reversal of 21042615 is 51624012.

It is an interprime number because it is at equal distance from previous prime (21042601) and next prime (21042629).

It is not a de Polignac number, because 21042615 - 2⁶ = 21042551 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21042591 and 21042600.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11172 + ... + 12918.

It is an arithmetic number, because the mean of its divisors is an integer number (1164168).

Almost surely, 2^21042615 is an apocalyptic number.

21042615 is a deficient number, since it is larger than the sum of its proper divisors (16210761).

21042615 is a wasteful number, since it uses less digits than its factorization.

21042615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1839.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21042615 is about 4587.2230161613. The cubic root of 21042615 is about 276.0789130580.

Adding to 21042615 its reverse (51624012), we get a palindrome (72666627).

The spelling of 21042615 in words is "twenty-one million, forty-two thousand, six hundred fifteen".