21552031 has 2 divisors, whose sum is σ = 21552032. Its totient is φ = 21552030.

The previous prime is 21552007. The next prime is 21552043. The reversal of 21552031 is 13025512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21552031 is a prime.

It is a super-2 number, since 2×21552031² = 928980080449922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21552131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776015 + 10776016.

It is an arithmetic number, because the mean of its divisors is an integer number (10776016).

Almost surely, 2^21552031 is an apocalyptic number.

21552031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21552031 is an equidigital number, since it uses as much as digits as its factorization.

21552031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21552031 is about 4642.4165043649. The cubic root of 21552031 is about 278.2890176097.

Adding to 21552031 its reverse (13025512), we get a palindrome (34577543).

It can be divided in two parts, 2155 and 2031, that added together give a triangular number (4186 = T₉₁).

The spelling of 21552031 in words is "twenty-one million, five hundred fifty-two thousand, thirty-one".