21951778698 has 24 divisors (see below), whose sum is σ = 47808630948. Its totient is φ = 7279345152.

The previous prime is 21951778697. The next prime is 21951778699. The reversal of 21951778698 is 89687715912.

21951778698 is a `hidden beast` number, since 21 + 9 + 517 + 7 + 8 + 6 + 98 = 666.

It is an interprime number because it is at equal distance from previous prime (21951778697) and next prime (21951778699).

It can be written as a sum of positive squares in 2 ways, for example, as 18582324489 + 3369454209 = 136317^2 + 58047^2 .

It is not an unprimeable number, because it can be changed into a prime (21951778697) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3155965 + ... + 3162912.

Almost surely, 2^21951778698 is an apocalyptic number.

21951778698 is an abundant number, since it is smaller than the sum of its proper divisors (25856852250).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21951778698 is a wasteful number, since it uses less digits than its factorization.

21951778698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6319078 (or 6319075 counting only the distinct ones).

The product of its digits is 15240960, while the sum is 63.

The spelling of 21951778698 in words is "twenty-one billion, nine hundred fifty-one million, seven hundred seventy-eight thousand, six hundred ninety-eight".