2978021981 has 16 divisors (see below), whose sum is σ = 3432422400. Its totient is φ = 2555290800.

The previous prime is 2978021957. The next prime is 2978021993. The reversal of 2978021981 is 1891208792.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2978021981 is a prime.

It is a super-2 number, since 2×2978021981² = 17737229838638328722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2978021951) 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, 30350 + ... + 82928.

It is an arithmetic number, because the mean of its divisors is an integer number (214526400).

Almost surely, 2^2978021981 is an apocalyptic number.

It is an amenable number.

2978021981 is a deficient number, since it is larger than the sum of its proper divisors (454400419).

2978021981 is a wasteful number, since it uses less digits than its factorization.

2978021981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52880.

The product of its (nonzero) digits is 145152, while the sum is 47.

The square root of 2978021981 is about 54571.2559961744. The cubic root of 2978021981 is about 1438.7189579613.

The spelling of 2978021981 in words is "two billion, nine hundred seventy-eight million, twenty-one thousand, nine hundred eighty-one".