47645721 has 12 divisors (see below), whose sum is σ = 69532372. Its totient is φ = 31435776.

The previous prime is 47645707. The next prime is 47645737. The reversal of 47645721 is 12754674.

47645721 is a `hidden beast` number, since 4 + 7 + 645 + 7 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 22695696 + 24950025 = 4764^2 + 4995^2 .

It is not a de Polignac number, because 47645721 - 2⁷ = 47645593 is a prime.

It is a super-2 number, since 2×47645721² = 4540229459219682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (47645021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26416 + ... + 28161.

Almost surely, 2^47645721 is an apocalyptic number.

It is an amenable number.

47645721 is a deficient number, since it is larger than the sum of its proper divisors (21886651).

47645721 is a wasteful number, since it uses less digits than its factorization.

47645721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54680 (or 54677 counting only the distinct ones).

The product of its digits is 47040, while the sum is 36.

The square root of 47645721 is about 6902.5879929198. The cubic root of 47645721 is about 362.5277879610.

The spelling of 47645721 in words is "forty-seven million, six hundred forty-five thousand, seven hundred twenty-one".