21978730994 has 16 divisors (see below), whose sum is σ = 35970907680. Its totient is φ = 9988745760.

The previous prime is 21978730981. The next prime is 21978730999. The reversal of 21978730994 is 49903787912.

It is a super-2 number, since 2×21978730994² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21978730999) 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, 68477 + ... + 220559.

It is an arithmetic number, because the mean of its divisors is an integer number (2248181730).

Almost surely, 2^21978730994 is an apocalyptic number.

21978730994 is a deficient number, since it is larger than the sum of its proper divisors (13992176686).

21978730994 is a wasteful number, since it uses less digits than its factorization.

21978730994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158665.

The product of its (nonzero) digits is 6858432, while the sum is 59.

The spelling of 21978730994 in words is "twenty-one billion, nine hundred seventy-eight million, seven hundred thirty thousand, nine hundred ninety-four".