3661772721 has 16 divisors (see below), whose sum is σ = 4967152320. Its totient is φ = 2398864320.

The previous prime is 3661772717. The next prime is 3661772729. The reversal of 3661772721 is 1272771663.

3661772721 is digitally balanced in base 2, base 3 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 3661772721 - 2² = 3661772717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3661772729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 193926 + ... + 211968.

It is an arithmetic number, because the mean of its divisors is an integer number (310447020).

Almost surely, 2^3661772721 is an apocalyptic number.

It is an amenable number.

3661772721 is a deficient number, since it is larger than the sum of its proper divisors (1305379599).

3661772721 is a wasteful number, since it uses less digits than its factorization.

3661772721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19216.

The product of its digits is 148176, while the sum is 42.

The square root of 3661772721 is about 60512.5831625126. The cubic root of 3661772721 is about 1541.3353124311.

The spelling of 3661772721 in words is "three billion, six hundred sixty-one million, seven hundred seventy-two thousand, seven hundred twenty-one".