4021981 has 8 divisors (see below), whose sum is σ = 4183200. Its totient is φ = 3862320.

The previous prime is 4021973. The next prime is 4022003. The reversal of 4021981 is 1891204.

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 4021981 - 2³ = 4021973 is a prime.

It is a super-2 number, since 2×4021981² = 32352662328722, 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 (4021961) 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, 9390 + ... + 9808.

It is an arithmetic number, because the mean of its divisors is an integer number (522900).

Almost surely, 2^4021981 is an apocalyptic number.

It is an amenable number.

4021981 is a deficient number, since it is larger than the sum of its proper divisors (161219).

4021981 is a wasteful number, since it uses less digits than its factorization.

4021981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 779.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 4021981 is about 2005.4877212289. The cubic root of 4021981 is about 159.0303463827.

The spelling of 4021981 in words is "four million, twenty-one thousand, nine hundred eighty-one".