155721456 has 120 divisors (see below), whose sum is σ = 488455344. Its totient is φ = 45895680.

The previous prime is 155721451. The next prime is 155721469. The reversal of 155721456 is 654127551.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 155721456.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155721451) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 57280 + ... + 59936.

Almost surely, 2^155721456 is an apocalyptic number.

155721456 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 155721456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (244227672).

155721456 is an abundant number, since it is smaller than the sum of its proper divisors (332733888).

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

155721456 is a wasteful number, since it uses less digits than its factorization.

155721456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2719 (or 2710 counting only the distinct ones).

The product of its digits is 42000, while the sum is 36.

The square root of 155721456 is about 12478.8403307359. The cubic root of 155721456 is about 538.0006725530. Note that the first 3 decimals are identical.

The spelling of 155721456 in words is "one hundred fifty-five million, seven hundred twenty-one thousand, four hundred fifty-six".