3905721 has 12 divisors (see below), whose sum is σ = 5824000. Its totient is φ = 2519640.

The previous prime is 3905717. The next prime is 3905753. The reversal of 3905721 is 1275093.

3905721 is a `hidden beast` number, since 3 + 90 + 572 + 1 = 666.

It is not a de Polignac number, because 3905721 - 2² = 3905717 is a prime.

It is a Duffinian number.

3905721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (3905711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6721 + ... + 7278.

Almost surely, 2^3905721 is an apocalyptic number.

3905721 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

3905721 is a deficient number, since it is larger than the sum of its proper divisors (1918279).

3905721 is a wasteful number, since it uses less digits than its factorization.

3905721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14036 (or 14033 counting only the distinct ones).

The product of its (nonzero) digits is 1890, while the sum is 27.

The square root of 3905721 is about 1976.2897054835. The cubic root of 3905721 is about 157.4830216014.

The spelling of 3905721 in words is "three million, nine hundred five thousand, seven hundred twenty-one".