121561612251 has 8 divisors (see below), whose sum is σ = 162095480640. Its totient is φ = 81034409352.

The previous prime is 121561612243. The next prime is 121561612273. The reversal of 121561612251 is 152216165121.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 121561612251 - 2³ = 121561612243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121561612351) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1623661 + ... + 1696878.

It is an arithmetic number, because the mean of its divisors is an integer number (20261935080).

Almost surely, 2^121561612251 is an apocalyptic number.

121561612251 is a deficient number, since it is larger than the sum of its proper divisors (40533868389).

121561612251 is a wasteful number, since it uses less digits than its factorization.

121561612251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3332745.

The product of its digits is 7200, while the sum is 33.

Adding to 121561612251 its reverse (152216165121), we get a palindrome (273777777372).

The spelling of 121561612251 in words is "one hundred twenty-one billion, five hundred sixty-one million, six hundred twelve thousand, two hundred fifty-one".