661038981 has 8 divisors (see below), whose sum is σ = 883652640. Its totient is φ = 439558992.

The previous prime is 661038977. The next prime is 661038991. The reversal of 661038981 is 189830166.

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

It is not a de Polignac number, because 661038981 - 2² = 661038977 is a prime.

It is a super-2 number, since 2×661038981² = 873945068803036722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661038901) 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, 282055 + ... + 284388.

It is an arithmetic number, because the mean of its divisors is an integer number (110456580).

Almost surely, 2^661038981 is an apocalyptic number.

It is an amenable number.

661038981 is a deficient number, since it is larger than the sum of its proper divisors (222613659).

661038981 is a wasteful number, since it uses less digits than its factorization.

661038981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566835.

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 661038981 is about 25710.6783457769. The cubic root of 661038981 is about 871.1153972267.

The spelling of 661038981 in words is "six hundred sixty-one million, thirty-eight thousand, nine hundred eighty-one".