20756981 has 8 divisors (see below), whose sum is σ = 23749824. Its totient is φ = 17771040.

The previous prime is 20756977. The next prime is 20756993. The reversal of 20756981 is 18965702.

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

It is not a de Polignac number, because 20756981 - 2² = 20756977 is a prime.

It is a super-2 number, since 2×20756981² = 861704520468722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20756941) 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, 11186 + ... + 12908.

It is an arithmetic number, because the mean of its divisors is an integer number (2968728).

Almost surely, 2^20756981 is an apocalyptic number.

It is an amenable number.

20756981 is a deficient number, since it is larger than the sum of its proper divisors (2992843).

20756981 is a wasteful number, since it uses less digits than its factorization.

20756981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3451.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 20756981 is about 4555.9829894327. The cubic root of 20756981 is about 274.8240461207.

The spelling of 20756981 in words is "twenty million, seven hundred fifty-six thousand, nine hundred eighty-one".