21481931 has 8 divisors (see below), whose sum is σ = 23734944. Its totient is φ = 19338880.

The previous prime is 21481927. The next prime is 21481939. The reversal of 21481931 is 13918412.

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

It is a cyclic number.

It is not a de Polignac number, because 21481931 - 2² = 21481927 is a prime.

It is a super-2 number, since 2×21481931² = 922946718977522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21481894 and 21481903.

It is not an unprimeable number, because it can be changed into a prime (21481939) 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, 27080 + ... + 27861.

It is an arithmetic number, because the mean of its divisors is an integer number (2966868).

Almost surely, 2^21481931 is an apocalyptic number.

21481931 is a deficient number, since it is larger than the sum of its proper divisors (2253013).

21481931 is a wasteful number, since it uses less digits than its factorization.

21481931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54981.

The product of its digits is 1728, while the sum is 29.

The square root of 21481931 is about 4634.8604078224. The cubic root of 21481931 is about 277.9869695254.

The spelling of 21481931 in words is "twenty-one million, four hundred eighty-one thousand, nine hundred thirty-one".