155721516 has 12 divisors (see below), whose sum is σ = 363350232. Its totient is φ = 51907168.

The previous prime is 155721499. The next prime is 155721521. The reversal of 155721516 is 615127551.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6488385 + ... + 6488408.

It is an arithmetic number, because the mean of its divisors is an integer number (30279186).

Almost surely, 2^155721516 is an apocalyptic number.

It is an amenable number.

155721516 is an abundant number, since it is smaller than the sum of its proper divisors (207628716).

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

155721516 is a wasteful number, since it uses less digits than its factorization.

155721516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12976800 (or 12976798 counting only the distinct ones).

The product of its digits is 10500, while the sum is 33.

The square root of 155721516 is about 12478.8427348052. The cubic root of 155721516 is about 538.0007416508. Note that the first 3 decimals are identical.

The spelling of 155721516 in words is "one hundred fifty-five million, seven hundred twenty-one thousand, five hundred sixteen".