31216661 has 12 divisors (see below), whose sum is σ = 36145632. Its totient is φ = 26409504.

The previous prime is 31216657. The next prime is 31216663. The reversal of 31216661 is 16661213.

It is not a de Polignac number, because 31216661 - 2² = 31216657 is a prime.

It is a super-4 number, since 4×31216661⁴ (a number of 31 digits) contains 4444 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31216661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31216663) 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, 55166 + ... + 55728.

It is an arithmetic number, because the mean of its divisors is an integer number (3012136).

Almost surely, 2^31216661 is an apocalyptic number.

It is an amenable number.

31216661 is a deficient number, since it is larger than the sum of its proper divisors (4928971).

31216661 is an frugal number, since it uses more digits than its factorization.

31216661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 748 (or 659 counting only the distinct ones).

The product of its digits is 1296, while the sum is 26.

The square root of 31216661 is about 5587.1872171961. The cubic root of 31216661 is about 314.8682105958.

Adding to 31216661 its reverse (16661213), we get a palindrome (47877874).

The spelling of 31216661 in words is "thirty-one million, two hundred sixteen thousand, six hundred sixty-one".