3909497721 has 4 divisors (see below), whose sum is σ = 5212663632. Its totient is φ = 2606331812.

The previous prime is 3909497629. The next prime is 3909497729. The reversal of 3909497721 is 1277949093.

3909497721 is digitally balanced in base 2 and base 4, because in such bases 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 a cyclic number.

It is not a de Polignac number, because 3909497721 - 2¹⁴ = 3909481337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3909497729) 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, 651582951 + ... + 651582956.

It is an arithmetic number, because the mean of its divisors is an integer number (1303165908).

Almost surely, 2^3909497721 is an apocalyptic number.

It is an amenable number.

3909497721 is a deficient number, since it is larger than the sum of its proper divisors (1303165911).

3909497721 is a wasteful number, since it uses less digits than its factorization.

3909497721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1303165910.

The product of its (nonzero) digits is 857304, while the sum is 51.

The square root of 3909497721 is about 62525.9763698257. The cubic root of 3909497721 is about 1575.3376578149.

The spelling of 3909497721 in words is "three billion, nine hundred nine million, four hundred ninety-seven thousand, seven hundred twenty-one".