21897771938 has 32 divisors (see below), whose sum is σ = 38690097024. Its totient is φ = 9098790912.

The previous prime is 21897771911. The next prime is 21897772027. The reversal of 21897771938 is 83917779812.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71906 + ... + 221282.

It is an arithmetic number, because the mean of its divisors is an integer number (1209065532).

Almost surely, 2^21897771938 is an apocalyptic number.

21897771938 is a deficient number, since it is larger than the sum of its proper divisors (16792325086).

21897771938 is a wasteful number, since it uses less digits than its factorization.

21897771938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149706.

The product of its digits is 10668672, while the sum is 62.

The spelling of 21897771938 in words is "twenty-one billion, eight hundred ninety-seven million, seven hundred seventy-one thousand, nine hundred thirty-eight".