21261564730 has 16 divisors (see below), whose sum is σ = 43738076160. Its totient is φ = 7289679312.

The previous prime is 21261564719. The next prime is 21261564767. The reversal of 21261564730 is 3746516212.

It is a self number, because there is not a number n which added to its sum of digits gives 21261564730.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151868250 + ... + 151868389.

It is an arithmetic number, because the mean of its divisors is an integer number (2733629760).

Almost surely, 2^21261564730 is an apocalyptic number.

21261564730 is an abundant number, since it is smaller than the sum of its proper divisors (22476511430).

21261564730 is a wasteful number, since it uses less digits than its factorization.

21261564730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 303736653.

The product of its (nonzero) digits is 60480, while the sum is 37.

The spelling of 21261564730 in words is "twenty-one billion, two hundred sixty-one million, five hundred sixty-four thousand, seven hundred thirty".