1981225461 has 4 divisors (see below), whose sum is σ = 2641633952. Its totient is φ = 1320816972.

The previous prime is 1981225447. The next prime is 1981225471. The reversal of 1981225461 is 1645221891.

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 an emirpimes, since its reverse is a distinct semiprime: 1645221891 = 3 ⋅548407297.

It is not a de Polignac number, because 1981225461 - 2¹⁴ = 1981209077 is a prime.

It is a super-3 number, since 3×1981225461³ (a number of 29 digits) contains 333 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 (1981225471) 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, 330204241 + ... + 330204246.

It is an arithmetic number, because the mean of its divisors is an integer number (660408488).

Almost surely, 2^1981225461 is an apocalyptic number.

It is an amenable number.

1981225461 is a deficient number, since it is larger than the sum of its proper divisors (660408491).

1981225461 is an equidigital number, since it uses as much as digits as its factorization.

1981225461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660408490.

The product of its digits is 34560, while the sum is 39.

The square root of 1981225461 is about 44510.9588865484. The cubic root of 1981225461 is about 1255.9662428636.

The spelling of 1981225461 in words is "one billion, nine hundred eighty-one million, two hundred twenty-five thousand, four hundred sixty-one".