2666749621 has 4 divisors (see below), whose sum is σ = 2666857600. Its totient is φ = 2666641644.

The previous prime is 2666749573. The next prime is 2666749639. The reversal of 2666749621 is 1269476662.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1269476662 = 2 ⋅634738331.

It is a cyclic number.

It is not a de Polignac number, because 2666749621 - 2⁷ = 2666749493 is a prime.

It is a super-2 number, since 2×2666749621² = 14223107082207287282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2666749661) 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, 3370 + ... + 73108.

It is an arithmetic number, because the mean of its divisors is an integer number (666714400).

Almost surely, 2^2666749621 is an apocalyptic number.

It is an amenable number.

2666749621 is a deficient number, since it is larger than the sum of its proper divisors (107979).

2666749621 is an equidigital number, since it uses as much as digits as its factorization.

2666749621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107978.

The product of its digits is 1306368, while the sum is 49.

The square root of 2666749621 is about 51640.5811450646. The cubic root of 2666749621 is about 1386.7369278827.

The spelling of 2666749621 in words is "two billion, six hundred sixty-six million, seven hundred forty-nine thousand, six hundred twenty-one".