121557731 has 4 divisors (see below), whose sum is σ = 122079672. Its totient is φ = 121035792.

The previous prime is 121557697. The next prime is 121557773. The reversal of 121557731 is 137755121.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121557731 is a prime.

It is a super-2 number, since 2×121557731² = 29552563931736722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121557131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260621 + ... + 261086.

It is an arithmetic number, because the mean of its divisors is an integer number (30519918).

Almost surely, 2^121557731 is an apocalyptic number.

121557731 is a deficient number, since it is larger than the sum of its proper divisors (521941).

121557731 is an equidigital number, since it uses as much as digits as its factorization.

121557731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521940.

The product of its digits is 7350, while the sum is 32.

The square root of 121557731 is about 11025.3222628638. The cubic root of 121557731 is about 495.3675208232.

The spelling of 121557731 in words is "one hundred twenty-one million, five hundred fifty-seven thousand, seven hundred thirty-one".