21154031 has 4 divisors (see below), whose sum is σ = 21178872. Its totient is φ = 21129192.

The previous prime is 21154027. The next prime is 21154039. The reversal of 21154031 is 13045112.

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 21154031 - 2² = 21154027 is a prime.

It is a super-2 number, since 2×21154031² = 894986055097922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11096 + ... + 12861.

It is an arithmetic number, because the mean of its divisors is an integer number (5294718).

Almost surely, 2^21154031 is an apocalyptic number.

21154031 is a deficient number, since it is larger than the sum of its proper divisors (24841).

21154031 is an equidigital number, since it uses as much as digits as its factorization.

21154031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24840.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21154031 is about 4599.3511498906. The cubic root of 21154031 is about 276.5653145638.

Adding to 21154031 its reverse (13045112), we get a palindrome (34199143).

The spelling of 21154031 in words is "twenty-one million, one hundred fifty-four thousand, thirty-one".