21042510 has 16 divisors (see below), whose sum is σ = 50502096. Its totient is φ = 5611328.

The previous prime is 21042491. The next prime is 21042533. The reversal of 21042510 is 1524012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21042510.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 350679 + ... + 350738.

It is an arithmetic number, because the mean of its divisors is an integer number (3156381).

Almost surely, 2^21042510 is an apocalyptic number.

21042510 is an abundant number, since it is smaller than the sum of its proper divisors (29459586).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21042510 is a wasteful number, since it uses less digits than its factorization.

21042510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701427.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21042510 is about 4587.2115713143. The cubic root of 21042510 is about 276.0784538576.

Adding to 21042510 its reverse (1524012), we get a palindrome (22566522).

The spelling of 21042510 in words is "twenty-one million, forty-two thousand, five hundred ten".