21860660 has 12 divisors (see below), whose sum is σ = 45907428. Its totient is φ = 8744256.

The previous prime is 21860651. The next prime is 21860689. The reversal of 21860660 is 6606812.

It can be written as a sum of positive squares in 2 ways, for example, as 16224784 + 5635876 = 4028^2 + 2374^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 546497 + ... + 546536.

It is an arithmetic number, because the mean of its divisors is an integer number (3825619).

Almost surely, 2^21860660 is an apocalyptic number.

21860660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21860660 is an abundant number, since it is smaller than the sum of its proper divisors (24046768).

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

21860660 is a wasteful number, since it uses less digits than its factorization.

21860660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1093042 (or 1093040 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 21860660 is about 4675.5384716629. The cubic root of 21860660 is about 279.6111097828.

The spelling of 21860660 in words is "twenty-one million, eight hundred sixty thousand, six hundred sixty".