21771953 has 8 divisors (see below), whose sum is σ = 25740480. Its totient is φ = 18018000.

The previous prime is 21771913. The next prime is 21771977. The reversal of 21771953 is 35917712.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-21771953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21771913) 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, 53423 + ... + 53828.

It is an arithmetic number, because the mean of its divisors is an integer number (3217560).

Almost surely, 2^21771953 is an apocalyptic number.

It is an amenable number.

21771953 is a deficient number, since it is larger than the sum of its proper divisors (3968527).

21771953 is a wasteful number, since it uses less digits than its factorization.

21771953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107287.

The product of its digits is 13230, while the sum is 35.

The square root of 21771953 is about 4666.0425415978. The cubic root of 21771953 is about 279.2323916040.

The spelling of 21771953 in words is "twenty-one million, seven hundred seventy-one thousand, nine hundred fifty-three".