21935661 has 32 divisors (see below), whose sum is σ = 34390656. Its totient is φ = 12288000.

The previous prime is 21935657. The next prime is 21935707. The reversal of 21935661 is 16653912.

It is a happy number.

It is not a de Polignac number, because 21935661 - 2² = 21935657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21935621) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33901 + ... + 34541.

It is an arithmetic number, because the mean of its divisors is an integer number (1074708).

Almost surely, 2^21935661 is an apocalyptic number.

It is an amenable number.

21935661 is a deficient number, since it is larger than the sum of its proper divisors (12454995).

21935661 is a wasteful number, since it uses less digits than its factorization.

21935661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733.

The product of its digits is 9720, while the sum is 33.

The square root of 21935661 is about 4683.5521775678. The cubic root of 21935661 is about 279.9305142202.

The spelling of 21935661 in words is "twenty-one million, nine hundred thirty-five thousand, six hundred sixty-one".