1961681 has 8 divisors (see below), whose sum is σ = 2089800. Its totient is φ = 1835008.

The previous prime is 1961671. The next prime is 1961683. The reversal of 1961681 is 1861691.

1961681 is nontrivially palindromic in base 16.

It can be written as a sum of positive squares in 4 ways, for example, as 1254400 + 707281 = 1120^2 + 841^2 .

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

It is a 5-Lehmer number, since φ(1961681) divides (1961681-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 1961681 - 2¹⁴ = 1945297 is a prime.

It is a super-2 number, since 2×1961681² = 7696384691522, 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 (1961683) 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, 4145 + ... + 4593.

It is an arithmetic number, because the mean of its divisors is an integer number (261225).

2^1961681 is an apocalyptic number.

It is an amenable number.

1961681 is a deficient number, since it is larger than the sum of its proper divisors (128119).

1961681 is a wasteful number, since it uses less digits than its factorization.

1961681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723.

The product of its digits is 2592, while the sum is 32.

The square root of 1961681 is about 1400.6002284735. The cubic root of 1961681 is about 125.1822621150.

It can be divided in two parts, 196 and 1681, that multiplied together give a square (329476 = 574²).

The spelling of 1961681 in words is "one million, nine hundred sixty-one thousand, six hundred eighty-one".