121557720 has 32 divisors (see below), whose sum is σ = 364673520. Its totient is φ = 32415360.

The previous prime is 121557697. The next prime is 121557773. The reversal of 121557720 is 27755121.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 506371 + ... + 506610.

Almost surely, 2^121557720 is an apocalyptic number.

121557720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

121557720 is an abundant number, since it is smaller than the sum of its proper divisors (243115800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

121557720 is a wasteful number, since it uses less digits than its factorization.

121557720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1012995 (or 1012991 counting only the distinct ones).

The product of its (nonzero) digits is 4900, while the sum is 30.

The square root of 121557720 is about 11025.3217640122. The cubic root of 121557720 is about 495.3675058809.

The spelling of 121557720 in words is "one hundred twenty-one million, five hundred fifty-seven thousand, seven hundred twenty".