121215155545 has 48 divisors (see below), whose sum is σ = 164351834640. Its totient is φ = 85697187840.

The previous prime is 121215155531. The next prime is 121215155549. The reversal of 121215155545 is 545551512121.

It can be written as a sum of positive squares in 8 ways, for example, as 1130035456 + 120085120089 = 33616^2 + 346533^2 .

It is not a de Polignac number, because 121215155545 - 2¹⁷ = 121215024473 is a prime.

It is a super-2 number, since 2×121215155545² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (121215155549) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 39239361 + ... + 39242449.

It is an arithmetic number, because the mean of its divisors is an integer number (3423996555).

Almost surely, 2^121215155545 is an apocalyptic number.

It is an amenable number.

121215155545 is a deficient number, since it is larger than the sum of its proper divisors (43136679095).

121215155545 is a wasteful number, since it uses less digits than its factorization.

121215155545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4906 (or 4895 counting only the distinct ones).

The product of its digits is 50000, while the sum is 37.

Adding to 121215155545 its reverse (545551512121), we get a palindrome (666766667666).

The spelling of 121215155545 in words is "one hundred twenty-one billion, two hundred fifteen million, one hundred fifty-five thousand, five hundred forty-five".