213121001 has 4 divisors (see below), whose sum is σ = 219995904. Its totient is φ = 206246100.

The previous prime is 213120979. The next prime is 213121019. The reversal of 213121001 is 100121312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 213121001 - 2¹⁸ = 212858857 is a prime.

It is a super-2 number, since 2×213121001² = 90841122134484002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (213121021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3437405 + ... + 3437466.

It is an arithmetic number, because the mean of its divisors is an integer number (54998976).

Almost surely, 2^213121001 is an apocalyptic number.

It is an amenable number.

213121001 is a deficient number, since it is larger than the sum of its proper divisors (6874903).

213121001 is an equidigital number, since it uses as much as digits as its factorization.

213121001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6874902.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 213121001 is about 14598.6643567143. The cubic root of 213121001 is about 597.3223280836.

Adding to 213121001 its reverse (100121312), we get a palindrome (313242313).

It can be divided in two parts, 21312 and 1001, that multiplied together give a palindrome (21333312).

The spelling of 213121001 in words is "two hundred thirteen million, one hundred twenty-one thousand, one".