661142981 has 12 divisors (see below), whose sum is σ = 728118432. Its totient is φ = 599106024.

The previous prime is 661142959. The next prime is 661142987. The reversal of 661142981 is 189241166.

It is not a de Polignac number, because 661142981 - 2¹⁸ = 660880837 is a prime.

It is a super-2 number, since 2×661142981² = 874220082651132722, 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 (661142987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31511 + ... + 48116.

It is an arithmetic number, because the mean of its divisors is an integer number (60676536).

Almost surely, 2^661142981 is an apocalyptic number.

It is an amenable number.

661142981 is a deficient number, since it is larger than the sum of its proper divisors (66975451).

661142981 is a wasteful number, since it uses less digits than its factorization.

661142981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79688 (or 79669 counting only the distinct ones).

The product of its digits is 20736, while the sum is 38.

The square root of 661142981 is about 25712.7007721865. The cubic root of 661142981 is about 871.1610784716.

The spelling of 661142981 in words is "six hundred sixty-one million, one hundred forty-two thousand, nine hundred eighty-one".