121557381 has 16 divisors (see below), whose sum is σ = 177104448. Its totient is φ = 73548800.

The previous prime is 121557367. The next prime is 121557419. The reversal of 121557381 is 183755121.

It is a cyclic number.

It is not a de Polignac number, because 121557381 - 2⁵ = 121557349 is a prime.

It is a super-2 number, since 2×121557381² = 29552393751158322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121557301) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19621 + ... + 25061.

It is an arithmetic number, because the mean of its divisors is an integer number (11069028).

Almost surely, 2^121557381 is an apocalyptic number.

121557381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

121557381 is a deficient number, since it is larger than the sum of its proper divisors (55547067).

121557381 is a wasteful number, since it uses less digits than its factorization.

121557381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6132.

The product of its digits is 8400, while the sum is 33.

The square root of 121557381 is about 11025.3063903005. The cubic root of 121557381 is about 495.3670453871.

The spelling of 121557381 in words is "one hundred twenty-one million, five hundred fifty-seven thousand, three hundred eighty-one".