21542515 has 8 divisors (see below), whose sum is σ = 25886448. Its totient is φ = 17210400.

The previous prime is 21542483. The next prime is 21542537. The reversal of 21542515 is 51524512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21542515 - 2⁵ = 21542483 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21542515.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1740 + ... + 6790.

It is an arithmetic number, because the mean of its divisors is an integer number (3235806).

Almost surely, 2^21542515 is an apocalyptic number.

21542515 is a deficient number, since it is larger than the sum of its proper divisors (4343933).

21542515 is an equidigital number, since it uses as much as digits as its factorization.

21542515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5909.

The product of its digits is 2000, while the sum is 25.

The square root of 21542515 is about 4641.3914939380. The cubic root of 21542515 is about 278.2480533630.

The spelling of 21542515 in words is "twenty-one million, five hundred forty-two thousand, five hundred fifteen".