121561551 has 24 divisors (see below), whose sum is σ = 178594416. Its totient is φ = 79664640.

The previous prime is 121561549. The next prime is 121561579. The reversal of 121561551 is 155165121.

It is not a de Polignac number, because 121561551 - 2¹ = 121561549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121561541) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 263461 + ... + 263921.

It is an arithmetic number, because the mean of its divisors is an integer number (7441434).

Almost surely, 2^121561551 is an apocalyptic number.

121561551 is a deficient number, since it is larger than the sum of its proper divisors (57032865).

121561551 is a wasteful number, since it uses less digits than its factorization.

121561551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903 (or 900 counting only the distinct ones).

The product of its digits is 1500, while the sum is 27.

The square root of 121561551 is about 11025.4954990694. The cubic root of 121561551 is about 495.3727098092.

The spelling of 121561551 in words is "one hundred twenty-one million, five hundred sixty-one thousand, five hundred fifty-one".