21006655770 has 32 divisors (see below), whose sum is σ = 50420233152. Its totient is φ = 5601301632.

The previous prime is 21006655739. The next prime is 21006655799. The reversal of 21006655770 is 7755660012.

It is a Curzon number.

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, 469494 + ... + 512286.

It is an arithmetic number, because the mean of its divisors is an integer number (1575632286).

Almost surely, 2^21006655770 is an apocalyptic number.

21006655770 is an abundant number, since it is smaller than the sum of its proper divisors (29413577382).

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

21006655770 is a wasteful number, since it uses less digits than its factorization.

21006655770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59166.

The product of its (nonzero) digits is 88200, while the sum is 39.

The spelling of 21006655770 in words is "twenty-one billion, six million, six hundred fifty-five thousand, seven hundred seventy".