20215121 has 4 divisors (see below), whose sum is σ = 20224512. Its totient is φ = 20205732.

The previous prime is 20215109. The next prime is 20215133. The reversal of 20215121 is 12151202.

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, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (20215109) and next prime (20215133).

It is a cyclic number.

It is not a de Polignac number, because 20215121 - 2¹⁰ = 20214097 is a prime.

It is a super-3 number, since 3×20215121³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20215096 and 20215105.

It is not an unprimeable number, because it can be changed into a prime (20215171) 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, 320 + ... + 6366.

It is an arithmetic number, because the mean of its divisors is an integer number (5056128).

Almost surely, 2^20215121 is an apocalyptic number.

It is an amenable number.

20215121 is a deficient number, since it is larger than the sum of its proper divisors (9391).

20215121 is an equidigital number, since it uses as much as digits as its factorization.

20215121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9390.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 20215121 is about 4496.1228853313. The cubic root of 20215121 is about 272.4115067702.

Adding to 20215121 its reverse (12151202), we get a palindrome (32366323).

The spelling of 20215121 in words is "twenty million, two hundred fifteen thousand, one hundred twenty-one".