1661667225 has 24 divisors (see below), whose sum is σ = 2821545600. Its totient is φ = 862269120.

The previous prime is 1661667191. The next prime is 1661667247. The reversal of 1661667225 is 5227661661.

It is not a de Polignac number, because 1661667225 - 2¹⁹ = 1661142937 is a prime.

It is a super-2 number, since 2×1661667225² = 5522275933278401250, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 296625 + ... + 302174.

It is an arithmetic number, because the mean of its divisors is an integer number (117564400).

Almost surely, 2^1661667225 is an apocalyptic number.

1661667225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661667225 is a deficient number, since it is larger than the sum of its proper divisors (1159878375).

1661667225 is a wasteful number, since it uses less digits than its factorization.

1661667225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 598849 (or 598844 counting only the distinct ones).

The product of its digits is 181440, while the sum is 42.

The square root of 1661667225 is about 40763.5526543014. The cubic root of 1661667225 is about 1184.4444154450. Note that the first 4 decimals are identical.

The spelling of 1661667225 in words is "one billion, six hundred sixty-one million, six hundred sixty-seven thousand, two hundred twenty-five".