21450031 has 4 divisors (see below), whose sum is σ = 22579000. Its totient is φ = 20321064.

The previous prime is 21450029. The next prime is 21450061. The reversal of 21450031 is 13005412.

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 21450031 - 2¹ = 21450029 is a prime.

It is a super-2 number, since 2×21450031² = 920207659801922, 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 = 21449987 and 21450014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450061) 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, 564456 + ... + 564493.

It is an arithmetic number, because the mean of its divisors is an integer number (5644750).

Almost surely, 2^21450031 is an apocalyptic number.

21450031 is a deficient number, since it is larger than the sum of its proper divisors (1128969).

21450031 is a wasteful number, since it uses less digits than its factorization.

21450031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1128968.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21450031 is about 4631.4178174723. The cubic root of 21450031 is about 277.8493006877.

Adding to 21450031 its reverse (13005412), we get a palindrome (34455443).

The spelling of 21450031 in words is "twenty-one million, four hundred fifty thousand, thirty-one".