21453031 has 4 divisors (see below), whose sum is σ = 22714992. Its totient is φ = 20191072.

The previous prime is 21453017. The next prime is 21453037. The reversal of 21453031 is 13035412.

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 21453031 - 2⁵ = 21452999 is a prime.

It is a super-2 number, since 2×21453031² = 920465078173922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21453037) 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, 630955 + ... + 630988.

It is an arithmetic number, because the mean of its divisors is an integer number (5678748).

Almost surely, 2^21453031 is an apocalyptic number.

21453031 is a deficient number, since it is larger than the sum of its proper divisors (1261961).

21453031 is a wasteful number, since it uses less digits than its factorization.

21453031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1261960.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21453031 is about 4631.7416810526. The cubic root of 21453031 is about 277.8622534125.

Adding to 21453031 its reverse (13035412), we get a palindrome (34488443).

The spelling of 21453031 in words is "twenty-one million, four hundred fifty-three thousand, thirty-one".