155720640 has 56 divisors (see below), whose sum is σ = 494416080. Its totient is φ = 41525248.

The previous prime is 155720627. The next prime is 155720641. The reversal of 155720640 is 46027551.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

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

It is a junction number, because it is equal to n+sod(n) for n = 155720598 and 155720607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155720641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80145 + ... + 82064.

Almost surely, 2^155720640 is an apocalyptic number.

155720640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

155720640 is an abundant number, since it is smaller than the sum of its proper divisors (338695440).

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

155720640 is a wasteful number, since it uses less digits than its factorization.

155720640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162229 (or 162219 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 155720640 is about 12478.8076353472. The cubic root of 155720640 is about 537.9997328210. Note that the first 3 decimals are identical.

The spelling of 155720640 in words is "one hundred fifty-five million, seven hundred twenty thousand, six hundred forty".