21387158 has 16 divisors (see below), whose sum is σ = 35392896. Its totient is φ = 9629760.

The previous prime is 21387151. The next prime is 21387161. The reversal of 21387158 is 85178312.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387151) 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 7 ways as a sum of consecutive naturals, for example, 8966 + ... + 11097.

It is an arithmetic number, because the mean of its divisors is an integer number (2212056).

Almost surely, 2^21387158 is an apocalyptic number.

21387158 is a deficient number, since it is larger than the sum of its proper divisors (14005738).

21387158 is a wasteful number, since it uses less digits than its factorization.

21387158 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20119.

The product of its digits is 13440, while the sum is 35.

The square root of 21387158 is about 4624.6251740006. The cubic root of 21387158 is about 277.5775634711.

It can be divided in two parts, 21 and 387158, that multiplied together give a palindrome (8130318).

The spelling of 21387158 in words is "twenty-one million, three hundred eighty-seven thousand, one hundred fifty-eight".