121581638 has 4 divisors (see below), whose sum is σ = 182372460. Its totient is φ = 60790818.

The previous prime is 121581631. The next prime is 121581653. The reversal of 121581638 is 836185121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 836185121 = 7297 ⋅114593.

It is a junction number, because it is equal to n+sod(n) for n = 121581598 and 121581607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121581631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30395408 + ... + 30395411.

It is an arithmetic number, because the mean of its divisors is an integer number (45593115).

Almost surely, 2^121581638 is an apocalyptic number.

121581638 is a deficient number, since it is larger than the sum of its proper divisors (60790822).

121581638 is an equidigital number, since it uses as much as digits as its factorization.

121581638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60790821.

The product of its digits is 11520, while the sum is 35.

The square root of 121581638 is about 11026.4063955579. The cubic root of 121581638 is about 495.3999936653.

The spelling of 121581638 in words is "one hundred twenty-one million, five hundred eighty-one thousand, six hundred thirty-eight".