21153087 has 12 divisors (see below), whose sum is σ = 30611880. Its totient is φ = 14075568.

The previous prime is 21153079. The next prime is 21153091. The reversal of 21153087 is 78035112.

It is not a de Polignac number, because 21153087 - 2³ = 21153079 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21153087.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21153017) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 3673 + ... + 7469.

It is an arithmetic number, because the mean of its divisors is an integer number (2550990).

Almost surely, 2^21153087 is an apocalyptic number.

21153087 is a deficient number, since it is larger than the sum of its proper divisors (9458793).

21153087 is a wasteful number, since it uses less digits than its factorization.

21153087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4422 (or 4419 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21153087 is about 4599.2485255746. The cubic root of 21153087 is about 276.5612005876.

Adding to 21153087 its reverse (78035112), we get a palindrome (99188199).

The spelling of 21153087 in words is "twenty-one million, one hundred fifty-three thousand, eighty-seven".