131661821 has 16 divisors (see below), whose sum is σ = 147256704. Its totient is φ = 117072384.

The previous prime is 131661809. The next prime is 131661833. The reversal of 131661821 is 128166131.

It is an interprime number because it is at equal distance from previous prime (131661809) and next prime (131661833).

It is a cyclic number.

It is not a de Polignac number, because 131661821 - 2²² = 127467517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131661221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30425 + ... + 34481.

It is an arithmetic number, because the mean of its divisors is an integer number (9203544).

Almost surely, 2^131661821 is an apocalyptic number.

It is an amenable number.

131661821 is a deficient number, since it is larger than the sum of its proper divisors (15594883).

131661821 is a wasteful number, since it uses less digits than its factorization.

131661821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4180.

The product of its digits is 1728, while the sum is 29.

The square root of 131661821 is about 11474.3985027539. The cubic root of 131661821 is about 508.7291451909.

The spelling of 131661821 in words is "one hundred thirty-one million, six hundred sixty-one thousand, eight hundred twenty-one".