253661981 has 8 divisors (see below), whose sum is σ = 270635904. Its totient is φ = 236916160.

The previous prime is 253661977. The next prime is 253661983. The reversal of 253661981 is 189166352.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 253661981 - 2² = 253661977 is a prime.

It is a super-2 number, since 2×253661981² = 128688801209688722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (253661983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54725 + ... + 59178.

It is an arithmetic number, because the mean of its divisors is an integer number (33829488).

Almost surely, 2^253661981 is an apocalyptic number.

It is an amenable number.

253661981 is a deficient number, since it is larger than the sum of its proper divisors (16973923).

253661981 is a wasteful number, since it uses less digits than its factorization.

253661981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114051.

The product of its digits is 77760, while the sum is 41.

The square root of 253661981 is about 15926.7693208635. The cubic root of 253661981 is about 633.0214989034.

The spelling of 253661981 in words is "two hundred fifty-three million, six hundred sixty-one thousand, nine hundred eighty-one".