21022221987 has 24 divisors (see below), whose sum is σ = 32950885968. Its totient is φ = 12837988800.

The previous prime is 21022221923. The next prime is 21022222007. The reversal of 21022221987 is 78912222012.

21022221987 is a `hidden beast` number, since 210 + 222 + 219 + 8 + 7 = 666.

It is not a de Polignac number, because 21022221987 - 2⁶ = 21022221923 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21022221907) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 670464 + ... + 701117.

It is an arithmetic number, because the mean of its divisors is an integer number (1372953582).

Almost surely, 2^21022221987 is an apocalyptic number.

21022221987 is a deficient number, since it is larger than the sum of its proper divisors (11928663981).

21022221987 is a wasteful number, since it uses less digits than its factorization.

21022221987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1371731 (or 1371728 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

Adding to 21022221987 its reverse (78912222012), we get a palindrome (99934443999).

The spelling of 21022221987 in words is "twenty-one billion, twenty-two million, two hundred twenty-one thousand, nine hundred eighty-seven".