21477661 has 8 divisors (see below), whose sum is σ = 22488480. Its totient is φ = 20484912.

The previous prime is 21477623. The next prime is 21477689. The reversal of 21477661 is 16677412.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21477661 - 2⁹ = 21477149 is a prime.

It is a super-2 number, since 2×21477661² = 922579844061842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21477601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2055 + ... + 6868.

It is an arithmetic number, because the mean of its divisors is an integer number (2811060).

Almost surely, 2^21477661 is an apocalyptic number.

It is an amenable number.

21477661 is a deficient number, since it is larger than the sum of its proper divisors (1010819).

21477661 is an equidigital number, since it uses as much as digits as its factorization.

21477661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9035.

The product of its digits is 14112, while the sum is 34.

The square root of 21477661 is about 4634.3997453824. The cubic root of 21477661 is about 277.9685496571.

The spelling of 21477661 in words is "twenty-one million, four hundred seventy-seven thousand, six hundred sixty-one".