1672447721 has 4 divisors (see below), whose sum is σ = 1911368832. Its totient is φ = 1433526612.

The previous prime is 1672447717. The next prime is 1672447729. The reversal of 1672447721 is 1277442761.

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 1672447721 - 2² = 1672447717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1672447729) 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, 119460545 + ... + 119460558.

It is an arithmetic number, because the mean of its divisors is an integer number (477842208).

Almost surely, 2^1672447721 is an apocalyptic number.

It is an amenable number.

1672447721 is a deficient number, since it is larger than the sum of its proper divisors (238921111).

1672447721 is an equidigital number, since it uses as much as digits as its factorization.

1672447721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238921110.

The product of its digits is 131712, while the sum is 41.

The square root of 1672447721 is about 40895.5709215558. The cubic root of 1672447721 is about 1187.0003591277. Note that the first 3 decimals are identical.

The spelling of 1672447721 in words is "one billion, six hundred seventy-two million, four hundred forty-seven thousand, seven hundred twenty-one".