20156121 has 28 divisors (see below), whose sum is σ = 30971248. Its totient is φ = 13104504.

The previous prime is 20156117. The next prime is 20156137. The reversal of 20156121 is 12165102.

It is not a de Polignac number, because 20156121 - 2² = 20156117 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20156094 and 20156103.

It is not an unprimeable number, because it can be changed into a prime (20156021) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 31026 + ... + 31668.

It is an arithmetic number, because the mean of its divisors is an integer number (1106116).

Almost surely, 2^20156121 is an apocalyptic number.

It is an amenable number.

20156121 is a deficient number, since it is larger than the sum of its proper divisors (10815127).

20156121 is an frugal number, since it uses more digits than its factorization.

20156121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 704 (or 689 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 20156121 is about 4489.5568823660. The cubic root of 20156121 is about 272.1462277821.

The spelling of 20156121 in words is "twenty million, one hundred fifty-six thousand, one hundred twenty-one".