21000061700 has 18 divisors (see below), whose sum is σ = 45570134106. Its totient is φ = 8400024640.

The previous prime is 21000061679. The next prime is 21000061763. The reversal of 21000061700 is 716000012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 3991206976 + 17008854724 = 63176^2 + 130418^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 105000209 + ... + 105000408.

It is an arithmetic number, because the mean of its divisors is an integer number (2531674117).

Almost surely, 2^21000061700 is an apocalyptic number.

21000061700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000061700 is an abundant number, since it is smaller than the sum of its proper divisors (24570072406).

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

21000061700 is a wasteful number, since it uses less digits than its factorization.

21000061700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210000631 (or 210000624 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 17.

Adding to 21000061700 its reverse (716000012), we get a palindrome (21716061712).

The spelling of 21000061700 in words is "twenty-one billion, sixty-one thousand, seven hundred".