21031887 has 8 divisors (see below), whose sum is σ = 28088704. Its totient is φ = 13998168.

The previous prime is 21031883. The next prime is 21031909. The reversal of 21031887 is 78813012.

It is a happy number.

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

It is not a de Polignac number, because 21031887 - 2² = 21031883 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3523 + ... + 7380.

It is an arithmetic number, because the mean of its divisors is an integer number (3511088).

Almost surely, 2^21031887 is an apocalyptic number.

21031887 is a deficient number, since it is larger than the sum of its proper divisors (7056817).

21031887 is a wasteful number, since it uses less digits than its factorization.

21031887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11549.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 21031887 is about 4586.0535321777. The cubic root of 21031887 is about 276.0319879959.

Adding to 21031887 its reverse (78813012), we get a palindrome (99844899).

The spelling of 21031887 in words is "twenty-one million, thirty-one thousand, eight hundred eighty-seven".