1554545721 has 4 divisors (see below), whose sum is σ = 2072727632. Its totient is φ = 1036363812.

The previous prime is 1554545717. The next prime is 1554545789. The reversal of 1554545721 is 1275454551.

1554545721 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1554545721 - 2² = 1554545717 is a prime.

It is a super-2 number, since 2×1554545721² = 4833224797358819682, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1554545721.

It is not an unprimeable number, because it can be changed into a prime (1554545621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 259090951 + ... + 259090956.

It is an arithmetic number, because the mean of its divisors is an integer number (518181908).

Almost surely, 2^1554545721 is an apocalyptic number.

It is an amenable number.

1554545721 is a deficient number, since it is larger than the sum of its proper divisors (518181911).

1554545721 is an equidigital number, since it uses as much as digits as its factorization.

1554545721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518181910.

The product of its digits is 140000, while the sum is 39.

The square root of 1554545721 is about 39427.7278193913. The cubic root of 1554545721 is about 1158.4247646039.

The spelling of 1554545721 in words is "one billion, five hundred fifty-four million, five hundred forty-five thousand, seven hundred twenty-one".