21038831 has 4 divisors (see below), whose sum is σ = 22951464. Its totient is φ = 19126200.

The previous prime is 21038821. The next prime is 21038837. The reversal of 21038831 is 13883012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21038831 - 2¹⁴ = 21022447 is a prime.

It is a super-2 number, since 2×21038831² = 885264819693122, which contains 22 as substring.

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 21038831.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21038837) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 956300 + ... + 956321.

It is an arithmetic number, because the mean of its divisors is an integer number (5737866).

Almost surely, 2^21038831 is an apocalyptic number.

21038831 is a deficient number, since it is larger than the sum of its proper divisors (1912633).

21038831 is a wasteful number, since it uses less digits than its factorization.

21038831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1912632.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21038831 is about 4586.8105476464. The cubic root of 21038831 is about 276.0623633844.

The spelling of 21038831 in words is "twenty-one million, thirty-eight thousand, eight hundred thirty-one".