21401766 has 32 divisors (see below), whose sum is σ = 47779200. Its totient is φ = 7101000.

The previous prime is 21401761. The next prime is 21401801. The reversal of 21401766 is 66710412.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12765 + ... + 14343.

It is an arithmetic number, because the mean of its divisors is an integer number (1493100).

Almost surely, 2^21401766 is an apocalyptic number.

21401766 is an abundant number, since it is smaller than the sum of its proper divisors (26377434).

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

21401766 is a wasteful number, since it uses less digits than its factorization.

21401766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1841 (or 1835 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21401766 is about 4626.2042756454. The cubic root of 21401766 is about 277.6407467173.

The spelling of 21401766 in words is "twenty-one million, four hundred one thousand, seven hundred sixty-six".