20661431 has 8 divisors (see below), whose sum is σ = 23640864. Its totient is φ = 17688960.

The previous prime is 20661419. The next prime is 20661437. The reversal of 20661431 is 13416602.

It is a happy number.

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 20661431 - 2⁶ = 20661367 is a prime.

It is a super-2 number, since 2×20661431² = 853789461935522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20661397 and 20661406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661437) 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, 9371 + ... + 11363.

It is an arithmetic number, because the mean of its divisors is an integer number (2955108).

Almost surely, 2^20661431 is an apocalyptic number.

20661431 is a deficient number, since it is larger than the sum of its proper divisors (2979433).

20661431 is a wasteful number, since it uses less digits than its factorization.

20661431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3481.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 20661431 is about 4545.4846826274. The cubic root of 20661431 is about 274.4017009176.

The spelling of 20661431 in words is "twenty million, six hundred sixty-one thousand, four hundred thirty-one".