20947551 has 8 divisors (see below), whose sum is σ = 27968304. Its totient is φ = 13945920.

The previous prime is 20947547. The next prime is 20947559. The reversal of 20947551 is 15574902.

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

It is not a de Polignac number, because 20947551 - 2² = 20947547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20947559) 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, 1990 + ... + 6771.

It is an arithmetic number, because the mean of its divisors is an integer number (3496038).

Almost surely, 2^20947551 is an apocalyptic number.

20947551 is a deficient number, since it is larger than the sum of its proper divisors (7020753).

20947551 is an equidigital number, since it uses as much as digits as its factorization.

20947551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9561.

The product of its (nonzero) digits is 12600, while the sum is 33.

The square root of 20947551 is about 4576.8494622393. The cubic root of 20947551 is about 275.6625391459.

The spelling of 20947551 in words is "twenty million, nine hundred forty-seven thousand, five hundred fifty-one".